Embryology - User contributions [en-gb]

User:Z3224500

2010-11-02T10:01:12Z

Z3224500: /* =attendance */

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:38, 28 July 2010 (UTC)

[[2010_Lecture_2|Cell Division]]

[http://www.smh.com.au/ SMH]

[[Fertilization|The egg and sperm]]

==Subheading==

==Picture==
[[File:Early_zygote.jpg|right]]

== Attendance ==
--[[User:Z3224500|Jenny Huang]] 23:36, 4 August 2010 (UTC)

===Search Pubmed===

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Prenatal%20Diagnosis Prenatal Diagnosis]

'''Search Pubmed Now:''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Prenatal%20Diagnosis Prenatal Diagnosis]
==Attendance==
--[[User:Z3224500|z3224500]] 23:13, 11 August 2010 (UTC)
==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:18, 18 August 2010 (UTC)

==Lab 2 Questions==
1. What factor do the synctiotrophoblast cells secrete to support the ongoing pregnancy?
hCG - human chorionic gonadotropin
2. What does the corpus luteum secrete to prevent continuation of the menstrual cycle?
It produces Estrogen and Progesterone

==Lab 3 Questions==

1. What Carnegie stages occur during week 3 and week 4?
Carnegie stages 7-9 occur during week 3 spanning days 15-21 and carnegie stages 10-13 occur spanning days 22-30.
2. What is the change in overall embryo size form the beginning of week 3 to the end of week 4?
From the beginning of week 3 the embryo is about 0.4mm and by the end of week 4 3-5mm.
3. Approximately when do the cranial (anterior) and caudal (posterior) neuropores close in the human embryo?
The anterior neuropore closes during carnegie stage 11 and the posterior neuropore closes at carnegie stage 13.

==Lab 4 Questions==
1. Name the vessels that drain into the sinus venosus?
The vitelline vein, umbilical vein and the cardinal vein drain into the sinus venosus.
2. What is the fate of the vitelline artery and vitelline vein?
The vitallene arteries contribute to the GI tract arteries and the vitallene veins contribute to the adult portal system.
3. Name the 4 layers that constitute the placental barrier?
The 4 cellular layers are in order : the syncitiotrophoblast, cytotrophoblast, villi connective tissues and fetal capillary endothelium
4. What stem cells are found in abundance, and may be harvested from the placenta for therapeutic uses?
Haematopoetic stem cells

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:22, 25 August 2010 (UTC)

==Lab 5 Questions==

1. What is the origin of the gastrointestinal tract smooth muscle?
The GIT smooth muscle is derived from the Splanchnic mesoderm that forms the smooth muscle, connective tissue, blood vessels and contributes to organ development.
2. At what Carnegie stage does the buccopharyngeal membrane begin to break down?
the buccopharyngeal membrane begins to break down during carnegie stage 11 opening the gastrointestinal tract to the amnion.
3. Identify the lung developmental stage in late embryonic to early fetal period.
During the late embryonic stage of lung development budding of the lungs from the trachea starts at around carnegie stage 22.
4. In premature infant birth, which respiratory cell type may not have fully developed?
Alveolar cells (type II) may not fully develop that are responsible for secreting surfactant.

==Attendance==
--[[User:Z3224500|Jenny]] 23:24, 1 September 2010 (UTC)
==Attendance==
(for 15 September, I forgot to sign on) --[[User:Z3224500|Jenny Huang]] 10:37, 19 September 2010 (UTC)

==Lab 7 Questions==

1. Briefly; what is a myotube and how is it formed?
A myotube is a nucleated muscle fibre that is non mature and developing. It is formed by the fusion of myoblasts.
2. What changes would I expect to see in the muscle fibre types in my legs if I:

a) Suffered a spinal cord injury

b) Took up marathon running

==Group Project Assessment==

'''Group 1 '''

Very informative page, nicely organised. Tables where very concise and clear, not cluttered. The technical aspects of ultrasound were covered really well, as well as the images accompanying them. Images were described in depth alongside the thumbnail.. however it wasn't too clear if there was a student drawn image on the page. Abnormalities were covered really well also, the information was easy to understand yet still being scientific in the language. I also liked how there were useful links throughout the page that relate to their topic. Things that could be improved would be on the Current Research heading, could be longer. References were good, with a nice glossary.

'''group 3'''

Layout was nicely organised, with logical flow and simple to understand. History was covered well, and prodedure was explained very thoroughly and was quite scientific yet simple about the information on what happens in the lab, ie. karotyping. I liked the student drawn images, they were quite informative and supplemented the text really well. Risks was covered in depth, and was interested to know about the psychological effects. Abnormalities were interesting, I found that the pie chart and the picture very eye catching, made it more interesting to learn about the topic. The table was neat and to the point, with added links which was helpful. The current research could be expanded upon though. Good references but missing glossary.

'''Group 4'''

Very good use of images. Very eye catching. Impressive student drawn figures, I thought it was very well done, shows the effort put in it and very informative and labelled very well. I liked the comparison with other prenatal techniques, showed that they have researched other techniques as well as their own. Procedure was covered nicely, although abnormalities detected could be elaborated upon with images to supplement the text, as I felt it was a little short, but nevertheless it was simple and easy to understand. CUrrent research should also be expanded upon. References were ok, I think more in text citations would be better, and a more longer glossary is probably better.

'''Group 5"

Simple, good organisation and what I like about it is that they referenced a lot of their text to backup their information which i thought was very scientific. The drawn picture was nice, but overall the page needed more images and pictures to understand the topic better. A table may have been a good choice to convey some information to make it more interesting, but it is still simple so not a very big deal there. So overall, more images, and I think more longer information under some headings would provide more extensive knowledge on the topic. References are very good, with an alright glossary.

'''group 6 '''

Good headings, but an error I noticed in the contents section was that the subheadings were all lumped under the "introduction" heading. History was a little brief, though I really liked the drawn images, it seemed like effort was put into drawing and labeling, and very informative. I thought information was scientific and explained alpha fetoprotein very well in a molecular point of view which meant they had done good research on the topic. More images would have made it more interesting in the abnormalities section, and also maybe a table that was implemented on the page would have been good because the thumbnail pictures of the tables were a little hard to see without clicking on them. But overall, good organisation, and good references.

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:33, 22 September 2010 (UTC)
==attendance==
--[[User:Z3224500|Jenny Huang]] 12:27, 6 October 2010 (UTC) (For September 30, forgot again, sorry)
==Attendance==
--[[User:Z3224500|z3224500]] 22:56, 6 October 2010 (UTC)

==Lab 10 Questions==

1. Development of which endocrine organ is affected by low dietary iodine?
The thyroid gland.
2. What are the affects of this deficiency on other non-endocrine system development?
Iodine deficiency can cause stunted growth and mental retardation. CHildren are incapable of normal movement, speech and hearing.
3. At approximately what week in development do many endocrine organs appear to begin their function?
They begin at approx. week 10

=attendance=
--[[User:Z3224500|Jenny Huang]] 08:00, 15 October 2010 (UTC)(october 14th)
==attendance==
--[[User:Z3224500|Jenny Huang]] 22:19, 20 October 2010 (UTC)

lab 12 Questions

1. During which trimester does fetal length change the most and when does fetal weight change the most?
fetal length changes most during the 2nd trimester and weight changes mostly in the third.
2. What is the name of the theory that links postnatal health with prenatal development?
Fetal Origins Hypothesis
3. Which hormone initiates and maintains labour during birth and where does it come from?
Oxytocin, which is secreted by the posterior pituitary gland in the mother. The fetus also has a role in producing oxytocin.

User:Z3224500

2010-11-02T10:00:50Z

Z3224500:

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:38, 28 July 2010 (UTC)

[[2010_Lecture_2|Cell Division]]

[http://www.smh.com.au/ SMH]

[[Fertilization|The egg and sperm]]

==Subheading==

==Picture==
[[File:Early_zygote.jpg|right]]

== Attendance ==
--[[User:Z3224500|Jenny Huang]] 23:36, 4 August 2010 (UTC)

===Search Pubmed===

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Prenatal%20Diagnosis Prenatal Diagnosis]

'''Search Pubmed Now:''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Prenatal%20Diagnosis Prenatal Diagnosis]
==Attendance==
--[[User:Z3224500|z3224500]] 23:13, 11 August 2010 (UTC)
==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:18, 18 August 2010 (UTC)

==Lab 2 Questions==
1. What factor do the synctiotrophoblast cells secrete to support the ongoing pregnancy?
hCG - human chorionic gonadotropin
2. What does the corpus luteum secrete to prevent continuation of the menstrual cycle?
It produces Estrogen and Progesterone

==Lab 3 Questions==

1. What Carnegie stages occur during week 3 and week 4?
Carnegie stages 7-9 occur during week 3 spanning days 15-21 and carnegie stages 10-13 occur spanning days 22-30.
2. What is the change in overall embryo size form the beginning of week 3 to the end of week 4?
From the beginning of week 3 the embryo is about 0.4mm and by the end of week 4 3-5mm.
3. Approximately when do the cranial (anterior) and caudal (posterior) neuropores close in the human embryo?
The anterior neuropore closes during carnegie stage 11 and the posterior neuropore closes at carnegie stage 13.

==Lab 4 Questions==
1. Name the vessels that drain into the sinus venosus?
The vitelline vein, umbilical vein and the cardinal vein drain into the sinus venosus.
2. What is the fate of the vitelline artery and vitelline vein?
The vitallene arteries contribute to the GI tract arteries and the vitallene veins contribute to the adult portal system.
3. Name the 4 layers that constitute the placental barrier?
The 4 cellular layers are in order : the syncitiotrophoblast, cytotrophoblast, villi connective tissues and fetal capillary endothelium
4. What stem cells are found in abundance, and may be harvested from the placenta for therapeutic uses?
Haematopoetic stem cells

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:22, 25 August 2010 (UTC)

==Lab 5 Questions==

1. What is the origin of the gastrointestinal tract smooth muscle?
The GIT smooth muscle is derived from the Splanchnic mesoderm that forms the smooth muscle, connective tissue, blood vessels and contributes to organ development.
2. At what Carnegie stage does the buccopharyngeal membrane begin to break down?
the buccopharyngeal membrane begins to break down during carnegie stage 11 opening the gastrointestinal tract to the amnion.
3. Identify the lung developmental stage in late embryonic to early fetal period.
During the late embryonic stage of lung development budding of the lungs from the trachea starts at around carnegie stage 22.
4. In premature infant birth, which respiratory cell type may not have fully developed?
Alveolar cells (type II) may not fully develop that are responsible for secreting surfactant.

==Attendance==
--[[User:Z3224500|Jenny]] 23:24, 1 September 2010 (UTC)
==Attendance==
(for 15 September, I forgot to sign on) --[[User:Z3224500|Jenny Huang]] 10:37, 19 September 2010 (UTC)

==Lab 7 Questions==

1. Briefly; what is a myotube and how is it formed?
A myotube is a nucleated muscle fibre that is non mature and developing. It is formed by the fusion of myoblasts.
2. What changes would I expect to see in the muscle fibre types in my legs if I:

a) Suffered a spinal cord injury

b) Took up marathon running

==Group Project Assessment==

'''Group 1 '''

Very informative page, nicely organised. Tables where very concise and clear, not cluttered. The technical aspects of ultrasound were covered really well, as well as the images accompanying them. Images were described in depth alongside the thumbnail.. however it wasn't too clear if there was a student drawn image on the page. Abnormalities were covered really well also, the information was easy to understand yet still being scientific in the language. I also liked how there were useful links throughout the page that relate to their topic. Things that could be improved would be on the Current Research heading, could be longer. References were good, with a nice glossary.

'''group 3'''

Layout was nicely organised, with logical flow and simple to understand. History was covered well, and prodedure was explained very thoroughly and was quite scientific yet simple about the information on what happens in the lab, ie. karotyping. I liked the student drawn images, they were quite informative and supplemented the text really well. Risks was covered in depth, and was interested to know about the psychological effects. Abnormalities were interesting, I found that the pie chart and the picture very eye catching, made it more interesting to learn about the topic. The table was neat and to the point, with added links which was helpful. The current research could be expanded upon though. Good references but missing glossary.

'''Group 4'''

Very good use of images. Very eye catching. Impressive student drawn figures, I thought it was very well done, shows the effort put in it and very informative and labelled very well. I liked the comparison with other prenatal techniques, showed that they have researched other techniques as well as their own. Procedure was covered nicely, although abnormalities detected could be elaborated upon with images to supplement the text, as I felt it was a little short, but nevertheless it was simple and easy to understand. CUrrent research should also be expanded upon. References were ok, I think more in text citations would be better, and a more longer glossary is probably better.

'''Group 5"

Simple, good organisation and what I like about it is that they referenced a lot of their text to backup their information which i thought was very scientific. The drawn picture was nice, but overall the page needed more images and pictures to understand the topic better. A table may have been a good choice to convey some information to make it more interesting, but it is still simple so not a very big deal there. So overall, more images, and I think more longer information under some headings would provide more extensive knowledge on the topic. References are very good, with an alright glossary.

'''group 6 '''

Good headings, but an error I noticed in the contents section was that the subheadings were all lumped under the "introduction" heading. History was a little brief, though I really liked the drawn images, it seemed like effort was put into drawing and labeling, and very informative. I thought information was scientific and explained alpha fetoprotein very well in a molecular point of view which meant they had done good research on the topic. More images would have made it more interesting in the abnormalities section, and also maybe a table that was implemented on the page would have been good because the thumbnail pictures of the tables were a little hard to see without clicking on them. But overall, good organisation, and good references.

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:33, 22 September 2010 (UTC)
==attendance==
--[[User:Z3224500|Jenny Huang]] 12:27, 6 October 2010 (UTC) (For September 30, forgot again, sorry)
==Attendance==
--[[User:Z3224500|z3224500]] 22:56, 6 October 2010 (UTC)

==Lab 10 Questions==

1. Development of which endocrine organ is affected by low dietary iodine?
The thyroid gland.
2. What are the affects of this deficiency on other non-endocrine system development?
Iodine deficiency can cause stunted growth and mental retardation. CHildren are incapable of normal movement, speech and hearing.
3. At approximately what week in development do many endocrine organs appear to begin their function?
They begin at approx. week 10

==attendance=
--[[User:Z3224500|Jenny Huang]] 08:00, 15 October 2010 (UTC)(october 14th)
==attendance==
--[[User:Z3224500|Jenny Huang]] 22:19, 20 October 2010 (UTC)

lab 12 Questions

1. During which trimester does fetal length change the most and when does fetal weight change the most?
fetal length changes most during the 2nd trimester and weight changes mostly in the third.
2. What is the name of the theory that links postnatal health with prenatal development?
Fetal Origins Hypothesis
3. Which hormone initiates and maintains labour during birth and where does it come from?
Oxytocin, which is secreted by the posterior pituitary gland in the mother. The fetus also has a role in producing oxytocin.

User:Z3224500

2010-10-20T22:19:31Z

Z3224500:

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:38, 28 July 2010 (UTC)

[[2010_Lecture_2|Cell Division]]

[http://www.smh.com.au/ SMH]

[[Fertilization|The egg and sperm]]

==Subheading==

==Picture==
[[File:Early_zygote.jpg|right]]

== Attendance ==
--[[User:Z3224500|Jenny Huang]] 23:36, 4 August 2010 (UTC)

===Search Pubmed===

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Prenatal%20Diagnosis Prenatal Diagnosis]

'''Search Pubmed Now:''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Prenatal%20Diagnosis Prenatal Diagnosis]
==Attendance==
--[[User:Z3224500|z3224500]] 23:13, 11 August 2010 (UTC)
==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:18, 18 August 2010 (UTC)

==Lab 2 Questions==
1. What factor do the synctiotrophoblast cells secrete to support the ongoing pregnancy?
hCG - human chorionic gonadotropin
2. What does the corpus luteum secrete to prevent continuation of the menstrual cycle?
It produces Estrogen and Progesterone

==Lab 3 Questions==

1. What Carnegie stages occur during week 3 and week 4?
Carnegie stages 7-9 occur during week 3 spanning days 15-21 and carnegie stages 10-13 occur spanning days 22-30.
2. What is the change in overall embryo size form the beginning of week 3 to the end of week 4?
From the beginning of week 3 the embryo is about 0.4mm and by the end of week 4 3-5mm.
3. Approximately when do the cranial (anterior) and caudal (posterior) neuropores close in the human embryo?
The anterior neuropore closes during carnegie stage 11 and the posterior neuropore closes at carnegie stage 13.

==Lab 4 Questions==
1. Name the vessels that drain into the sinus venosus?
The vitelline vein, umbilical vein and the cardinal vein drain into the sinus venosus.
2. What is the fate of the vitelline artery and vitelline vein?
The vitallene arteries contribute to the GI tract arteries and the vitallene veins contribute to the adult portal system.
3. Name the 4 layers that constitute the placental barrier?
The 4 cellular layers are in order : the syncitiotrophoblast, cytotrophoblast, villi connective tissues and fetal capillary endothelium
4. What stem cells are found in abundance, and may be harvested from the placenta for therapeutic uses?
Haematopoetic stem cells

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:22, 25 August 2010 (UTC)

==Lab 5 Questions==

1. What is the origin of the gastrointestinal tract smooth muscle?
The GIT smooth muscle is derived from the Splanchnic mesoderm that forms the smooth muscle, connective tissue, blood vessels and contributes to organ development.
2. At what Carnegie stage does the buccopharyngeal membrane begin to break down?
the buccopharyngeal membrane begins to break down during carnegie stage 11 opening the gastrointestinal tract to the amnion.
3. Identify the lung developmental stage in late embryonic to early fetal period.
During the late embryonic stage of lung development budding of the lungs from the trachea starts at around carnegie stage 22.
4. In premature infant birth, which respiratory cell type may not have fully developed?
Alveolar cells (type II) may not fully develop that are responsible for secreting surfactant.

==Attendance==
--[[User:Z3224500|Jenny]] 23:24, 1 September 2010 (UTC)
==Attendance==
(for 15 September, I forgot to sign on) --[[User:Z3224500|Jenny Huang]] 10:37, 19 September 2010 (UTC)

==Lab 7 Questions==

1. Briefly; what is a myotube and how is it formed?
A myotube is a nucleated muscle fibre that is non mature and developing. It is formed by the fusion of myoblasts.
2. What changes would I expect to see in the muscle fibre types in my legs if I:

a) Suffered a spinal cord injury

b) Took up marathon running

==Group Project Assessment==

'''Group 1 '''

Very informative page, nicely organised. Tables where very concise and clear, not cluttered. The technical aspects of ultrasound were covered really well, as well as the images accompanying them. Images were described in depth alongside the thumbnail.. however it wasn't too clear if there was a student drawn image on the page. Abnormalities were covered really well also, the information was easy to understand yet still being scientific in the language. I also liked how there were useful links throughout the page that relate to their topic. Things that could be improved would be on the Current Research heading, could be longer. References were good, with a nice glossary.

'''group 3'''

Layout was nicely organised, with logical flow and simple to understand. History was covered well, and prodedure was explained very thoroughly and was quite scientific yet simple about the information on what happens in the lab, ie. karotyping. I liked the student drawn images, they were quite informative and supplemented the text really well. Risks was covered in depth, and was interested to know about the psychological effects. Abnormalities were interesting, I found that the pie chart and the picture very eye catching, made it more interesting to learn about the topic. The table was neat and to the point, with added links which was helpful. The current research could be expanded upon though. Good references but missing glossary.

'''Group 4'''

Very good use of images. Very eye catching. Impressive student drawn figures, I thought it was very well done, shows the effort put in it and very informative and labelled very well. I liked the comparison with other prenatal techniques, showed that they have researched other techniques as well as their own. Procedure was covered nicely, although abnormalities detected could be elaborated upon with images to supplement the text, as I felt it was a little short, but nevertheless it was simple and easy to understand. CUrrent research should also be expanded upon. References were ok, I think more in text citations would be better, and a more longer glossary is probably better.

'''Group 5"

Simple, good organisation and what I like about it is that they referenced a lot of their text to backup their information which i thought was very scientific. The drawn picture was nice, but overall the page needed more images and pictures to understand the topic better. A table may have been a good choice to convey some information to make it more interesting, but it is still simple so not a very big deal there. So overall, more images, and I think more longer information under some headings would provide more extensive knowledge on the topic. References are very good, with an alright glossary.

'''group 6 '''

Good headings, but an error I noticed in the contents section was that the subheadings were all lumped under the "introduction" heading. History was a little brief, though I really liked the drawn images, it seemed like effort was put into drawing and labeling, and very informative. I thought information was scientific and explained alpha fetoprotein very well in a molecular point of view which meant they had done good research on the topic. More images would have made it more interesting in the abnormalities section, and also maybe a table that was implemented on the page would have been good because the thumbnail pictures of the tables were a little hard to see without clicking on them. But overall, good organisation, and good references.

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:33, 22 September 2010 (UTC)
==attendance==
--[[User:Z3224500|Jenny Huang]] 12:27, 6 October 2010 (UTC) (For September 30, forgot again, sorry)
==Attendance==
--[[User:Z3224500|z3224500]] 22:56, 6 October 2010 (UTC)

==Lab 10 Questions==

1. Development of which endocrine organ is affected by low dietary iodine?
The thyroid gland.
2. What are the affects of this deficiency on other non-endocrine system development?
Iodine deficiency can cause stunted growth and mental retardation. CHildren are incapable of normal movement, speech and hearing.
3. At approximately what week in development do many endocrine organs appear to begin their function?
They begin at approx. week 10

==attendance=
--[[User:Z3224500|Jenny Huang]] 08:00, 15 October 2010 (UTC)(october 14th)
==attendance==
--[[User:Z3224500|Jenny Huang]] 22:19, 20 October 2010 (UTC)

User:Z3224500

2010-10-15T08:00:10Z

Z3224500:

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:38, 28 July 2010 (UTC)

[[2010_Lecture_2|Cell Division]]

[http://www.smh.com.au/ SMH]

[[Fertilization|The egg and sperm]]

==Subheading==

==Picture==
[[File:Early_zygote.jpg|right]]

== Attendance ==
--[[User:Z3224500|Jenny Huang]] 23:36, 4 August 2010 (UTC)

===Search Pubmed===

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Prenatal%20Diagnosis Prenatal Diagnosis]

'''Search Pubmed Now:''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Prenatal%20Diagnosis Prenatal Diagnosis]
==Attendance==
--[[User:Z3224500|z3224500]] 23:13, 11 August 2010 (UTC)
==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:18, 18 August 2010 (UTC)

==Lab 2 Questions==
1. What factor do the synctiotrophoblast cells secrete to support the ongoing pregnancy?
hCG - human chorionic gonadotropin
2. What does the corpus luteum secrete to prevent continuation of the menstrual cycle?
It produces Estrogen and Progesterone

==Lab 3 Questions==

1. What Carnegie stages occur during week 3 and week 4?
Carnegie stages 7-9 occur during week 3 spanning days 15-21 and carnegie stages 10-13 occur spanning days 22-30.
2. What is the change in overall embryo size form the beginning of week 3 to the end of week 4?
From the beginning of week 3 the embryo is about 0.4mm and by the end of week 4 3-5mm.
3. Approximately when do the cranial (anterior) and caudal (posterior) neuropores close in the human embryo?
The anterior neuropore closes during carnegie stage 11 and the posterior neuropore closes at carnegie stage 13.

==Lab 4 Questions==
1. Name the vessels that drain into the sinus venosus?
The vitelline vein, umbilical vein and the cardinal vein drain into the sinus venosus.
2. What is the fate of the vitelline artery and vitelline vein?
The vitallene arteries contribute to the GI tract arteries and the vitallene veins contribute to the adult portal system.
3. Name the 4 layers that constitute the placental barrier?
The 4 cellular layers are in order : the syncitiotrophoblast, cytotrophoblast, villi connective tissues and fetal capillary endothelium
4. What stem cells are found in abundance, and may be harvested from the placenta for therapeutic uses?
Haematopoetic stem cells

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:22, 25 August 2010 (UTC)

==Lab 5 Questions==

1. What is the origin of the gastrointestinal tract smooth muscle?
The GIT smooth muscle is derived from the Splanchnic mesoderm that forms the smooth muscle, connective tissue, blood vessels and contributes to organ development.
2. At what Carnegie stage does the buccopharyngeal membrane begin to break down?
the buccopharyngeal membrane begins to break down during carnegie stage 11 opening the gastrointestinal tract to the amnion.
3. Identify the lung developmental stage in late embryonic to early fetal period.
During the late embryonic stage of lung development budding of the lungs from the trachea starts at around carnegie stage 22.
4. In premature infant birth, which respiratory cell type may not have fully developed?
Alveolar cells (type II) may not fully develop that are responsible for secreting surfactant.

==Attendance==
--[[User:Z3224500|Jenny]] 23:24, 1 September 2010 (UTC)
==Attendance==
(for 15 September, I forgot to sign on) --[[User:Z3224500|Jenny Huang]] 10:37, 19 September 2010 (UTC)

==Lab 7 Questions==

1. Briefly; what is a myotube and how is it formed?
A myotube is a nucleated muscle fibre that is non mature and developing. It is formed by the fusion of myoblasts.
2. What changes would I expect to see in the muscle fibre types in my legs if I:

a) Suffered a spinal cord injury

b) Took up marathon running

==Group Project Assessment==

'''Group 1 '''

Very informative page, nicely organised. Tables where very concise and clear, not cluttered. The technical aspects of ultrasound were covered really well, as well as the images accompanying them. Images were described in depth alongside the thumbnail.. however it wasn't too clear if there was a student drawn image on the page. Abnormalities were covered really well also, the information was easy to understand yet still being scientific in the language. I also liked how there were useful links throughout the page that relate to their topic. Things that could be improved would be on the Current Research heading, could be longer. References were good, with a nice glossary.

'''group 3'''

Layout was nicely organised, with logical flow and simple to understand. History was covered well, and prodedure was explained very thoroughly and was quite scientific yet simple about the information on what happens in the lab, ie. karotyping. I liked the student drawn images, they were quite informative and supplemented the text really well. Risks was covered in depth, and was interested to know about the psychological effects. Abnormalities were interesting, I found that the pie chart and the picture very eye catching, made it more interesting to learn about the topic. The table was neat and to the point, with added links which was helpful. The current research could be expanded upon though. Good references but missing glossary.

'''Group 4'''

Very good use of images. Very eye catching. Impressive student drawn figures, I thought it was very well done, shows the effort put in it and very informative and labelled very well. I liked the comparison with other prenatal techniques, showed that they have researched other techniques as well as their own. Procedure was covered nicely, although abnormalities detected could be elaborated upon with images to supplement the text, as I felt it was a little short, but nevertheless it was simple and easy to understand. CUrrent research should also be expanded upon. References were ok, I think more in text citations would be better, and a more longer glossary is probably better.

'''Group 5"

Simple, good organisation and what I like about it is that they referenced a lot of their text to backup their information which i thought was very scientific. The drawn picture was nice, but overall the page needed more images and pictures to understand the topic better. A table may have been a good choice to convey some information to make it more interesting, but it is still simple so not a very big deal there. So overall, more images, and I think more longer information under some headings would provide more extensive knowledge on the topic. References are very good, with an alright glossary.

'''group 6 '''

Good headings, but an error I noticed in the contents section was that the subheadings were all lumped under the "introduction" heading. History was a little brief, though I really liked the drawn images, it seemed like effort was put into drawing and labeling, and very informative. I thought information was scientific and explained alpha fetoprotein very well in a molecular point of view which meant they had done good research on the topic. More images would have made it more interesting in the abnormalities section, and also maybe a table that was implemented on the page would have been good because the thumbnail pictures of the tables were a little hard to see without clicking on them. But overall, good organisation, and good references.

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:33, 22 September 2010 (UTC)
==attendance==
--[[User:Z3224500|Jenny Huang]] 12:27, 6 October 2010 (UTC) (For September 30, forgot again, sorry)
==Attendance==
--[[User:Z3224500|z3224500]] 22:56, 6 October 2010 (UTC)

==Lab 10 Questions==

1. Development of which endocrine organ is affected by low dietary iodine?
The thyroid gland.
2. What are the affects of this deficiency on other non-endocrine system development?
Iodine deficiency can cause stunted growth and mental retardation. CHildren are incapable of normal movement, speech and hearing.
3. At approximately what week in development do many endocrine organs appear to begin their function?
They begin at approx. week 10

==attendance==
--[[User:Z3224500|Jenny Huang]] 08:00, 15 October 2010 (UTC)(october 14th)

File:Suctionaspiration.png

2010-10-13T22:37:57Z

Z3224500:

=Labels=
1. Amniotic sac
2. Embryo
3. Uterine lining
4. Speculum
5. Vacurette
6.The vacurette is attached to a suction pump

Copyright Information:

This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

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Image sourced from: http://en.wikipedia.org/wiki/File:Vacuum-aspiration_(single).svg

User:Z3224500

2010-10-13T11:55:39Z

Z3224500:

User:Z3224500

2010-10-12T14:12:17Z

Z3224500:

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:38, 28 July 2010 (UTC)

[[2010_Lecture_2|Cell Division]]

[http://www.smh.com.au/ SMH]

[[Fertilization|The egg and sperm]]

==Subheading==

==Picture==
[[File:Early_zygote.jpg|right]]

== Attendance ==
--[[User:Z3224500|Jenny Huang]] 23:36, 4 August 2010 (UTC)

===Search Pubmed===

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Prenatal%20Diagnosis Prenatal Diagnosis]

'''Search Pubmed Now:''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Prenatal%20Diagnosis Prenatal Diagnosis]
==Attendance==
--[[User:Z3224500|z3224500]] 23:13, 11 August 2010 (UTC)
==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:18, 18 August 2010 (UTC)

==Lab 2 Questions==
1. What factor do the synctiotrophoblast cells secrete to support the ongoing pregnancy?
hCG - human chorionic gonadotropin
2. What does the corpus luteum secrete to prevent continuation of the menstrual cycle?
It produces Estrogen and Progesterone

==Lab 3 Questions==

1. What Carnegie stages occur during week 3 and week 4?
Carnegie stages 7-9 occur during week 3 spanning days 15-21 and carnegie stages 10-13 occur spanning days 22-30.
2. What is the change in overall embryo size form the beginning of week 3 to the end of week 4?
From the beginning of week 3 the embryo is about 0.4mm and by the end of week 4 3-5mm.
3. Approximately when do the cranial (anterior) and caudal (posterior) neuropores close in the human embryo?
The anterior neuropore closes during carnegie stage 11 and the posterior neuropore closes at carnegie stage 13.

==Lab 4 Questions==
1. Name the vessels that drain into the sinus venosus?
The vitelline vein, umbilical vein and the cardinal vein drain into the sinus venosus.
2. What is the fate of the vitelline artery and vitelline vein?
The vitallene arteries contribute to the GI tract arteries and the vitallene veins contribute to the adult portal system.
3. Name the 4 layers that constitute the placental barrier?
The 4 cellular layers are in order : the syncitiotrophoblast, cytotrophoblast, villi connective tissues and fetal capillary endothelium
4. What stem cells are found in abundance, and may be harvested from the placenta for therapeutic uses?
Haematopoetic stem cells

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:22, 25 August 2010 (UTC)

==Lab 5 Questions==

1. What is the origin of the gastrointestinal tract smooth muscle?
The GIT smooth muscle is derived from the Splanchnic mesoderm that forms the smooth muscle, connective tissue, blood vessels and contributes to organ development.
2. At what Carnegie stage does the buccopharyngeal membrane begin to break down?
the buccopharyngeal membrane begins to break down during carnegie stage 11 opening the gastrointestinal tract to the amnion.
3. Identify the lung developmental stage in late embryonic to early fetal period.
During the late embryonic stage of lung development budding of the lungs from the trachea starts at around carnegie stage 22.
4. In premature infant birth, which respiratory cell type may not have fully developed?
Alveolar cells (type II) may not fully develop that are responsible for secreting surfactant.

==Attendance==
--[[User:Z3224500|Jenny]] 23:24, 1 September 2010 (UTC)
==Attendance==
(for 15 September, I forgot to sign on) --[[User:Z3224500|Jenny Huang]] 10:37, 19 September 2010 (UTC)

==Lab 7 Questions==

1. Briefly; what is a myotube and how is it formed?
A myotube is a nucleated muscle fibre that is non mature and developing. It is formed by the fusion of myoblasts.
2. What changes would I expect to see in the muscle fibre types in my legs if I:

a) Suffered a spinal cord injury

b) Took up marathon running

==Group Project Assessment==

'''Group 1 '''

Very informative page, nicely organised. Tables where very concise and clear, not cluttered. The technical aspects of ultrasound were covered really well, as well as the images accompanying them. Images were described in depth alongside the thumbnail.. however it wasn't too clear if there was a student drawn image on the page. Abnormalities were covered really well also, the information was easy to understand yet still being scientific in the language. I also liked how there were useful links throughout the page that relate to their topic. Things that could be improved would be on the Current Research heading, could be longer. References were good, with a nice glossary.

'''group 3'''

Layout was nicely organised, with logical flow and simple to understand. History was covered well, and prodedure was explained very thoroughly and was quite scientific yet simple about the information on what happens in the lab, ie. karotyping. I liked the student drawn images, they were quite informative and supplemented the text really well. Risks was covered in depth, and was interested to know about the psychological effects. Abnormalities were interesting, I found that the pie chart and the picture very eye catching, made it more interesting to learn about the topic. The table was neat and to the point, with added links which was helpful. The current research could be expanded upon though. Good references but missing glossary.

'''Group 4'''

Very good use of images. Very eye catching. Impressive student drawn figures, I thought it was very well done, shows the effort put in it and very informative and labelled very well. I liked the comparison with other prenatal techniques, showed that they have researched other techniques as well as their own. Procedure was covered nicely, although abnormalities detected could be elaborated upon with images to supplement the text, as I felt it was a little short, but nevertheless it was simple and easy to understand. CUrrent research should also be expanded upon. References were ok, I think more in text citations would be better, and a more longer glossary is probably better.

'''Group 5"

Simple, good organisation and what I like about it is that they referenced a lot of their text to backup their information which i thought was very scientific. The drawn picture was nice, but overall the page needed more images and pictures to understand the topic better. A table may have been a good choice to convey some information to make it more interesting, but it is still simple so not a very big deal there. So overall, more images, and I think more longer information under some headings would provide more extensive knowledge on the topic. References are very good, with an alright glossary.

'''group 6 '''

Good headings, but an error I noticed in the contents section was that the subheadings were all lumped under the "introduction" heading. History was a little brief, though I really liked the drawn images, it seemed like effort was put into drawing and labeling, and very informative. I thought information was scientific and explained alpha fetoprotein very well in a molecular point of view which meant they had done good research on the topic. More images would have made it more interesting in the abnormalities section, and also maybe a table that was implemented on the page would have been good because the thumbnail pictures of the tables were a little hard to see without clicking on them. But overall, good organisation, and good references.

==Attendance==
--[[User:Z3224500|Jenny Huang]] 23:33, 22 September 2010 (UTC)
==attendance==
--[[User:Z3224500|Jenny Huang]] 12:27, 6 October 2010 (UTC) (For September 30, forgot again, sorry)
==Attendance==
--[[User:Z3224500|z3224500]] 22:56, 6 October 2010 (UTC)

==Lab 10 Questions==

1. Development of which endocrine organ is affected by low dietary iodine?
The thyroid gland.
2. What are the affects of this deficiency on other non-endocrine system development?

3. At approximately what week in development do many endocrine organs appear to begin their function?

File:Transabdominal CVS.jpg

2010-10-07T23:58:13Z

Z3224500:

The Transabdominal procedure for chorionic villus sampling (CVS). A hollow needle is passed through to the placenta and a sample of the villi from the chorion is taken for testing.

"Beginning six months after publication, I (z3224500) grant the public the non-exclusive right to copy, distribute, or display the Work under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/ and http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode."
--[[User:Z3224500|z3224500]] 22:52, 26 September 2010 (UTC)

User:Z3224500

2010-10-06T22:56:05Z

Z3224500:

2010 Group Project 2

2010-10-06T13:47:33Z

Z3224500: /* Limitations */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=
[[File:Gray37.png|right|thumb|280px|Sample is taken from the chorionic villi]]
[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. Between 10-12 weeks of pregnancy, the developing gestational sac is composed of a thick, outer chorionic membrane surrounding the amniotic cavity, a thin amniotic membrane and the chorionic cavity. The chorionic villi have now degenerated over most of the outer membrane, forming the chorion laeve, and the remaining villi fuses and embeds loosely into the decidua basalis. This forms the chorion frondosum, which will ultimately become the placenta. At this stage, the villi float freely in the blood of the intervillus space. Each villi is branched, and is composed of an outer syncytiotrophoblast and an inner cytotrophoblast layer. Within the centre of each villus is a mesenchymal core which contain capillaries carrying fetal blood. In CVS, usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.<ref>Jenkins, T.M, Wapner, R.J, 1999. First trimester prenatal diagnosis: Chorionic villus sampling. Seminars in Perinatology. pp403-413.</ref>

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.<ref><pubmed>6855813</pubmed></ref>

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. Women who had transcervical sampling had higher occurrence of fluid leakage and spotting. When a tenaculum is not used, the occurrence of vaginal spotting and bleeding continued. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory, which is a laboratory that analyses the number and shape of the chromosomes in cells. At the laboratory the cells are cultured (stimulated to grow and divide) for approximately 12 days. After enough cells are cultured, a banded karyotype is completed. This is where the fetal chromosomes in the cultured cells are stained and then photographed. The photographed chromosomes are then ordered, counted and checked for abnormalities.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.
[[file:suctionaspiration.png|thumb|right|200px|Suction Aspiration technique. Enlarge for labels.]]
Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors.<ref>Cica. N., 1998. Abortion Law in Australia. Parliament of Australia, Parliamentary Library. Accessed September 29. 2010. <http://www.aph.gov.au/library/pubs/rp/1998-99/99rp01.htm></ref> If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems.<ref>Medline Plus: Trusted Health Information for You. 2010. Down's Syndrome. Accessed Septemeber 28, 2010.<http://www.nlm.nih.gov/medlineplus/ency/article/000997.htm></ref> Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.<ref>Roizen, N., Patterson, D., 2003. Down's syndrome. The Lancet. 361:1281-1289</ref>

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

'''Bioethics'''

The Bioethics involved in Health Care that encompasses medical practices including prenatal diagnosis methods aim to ensure that human values are respected in terms of healthcare institutions, life technology, health professions and clinical practices.<ref>Southern Cross Bioethics Institute. 2008. Bioethical Issues. Accessed 6 October, 2010. <http://www.bioethics.org.au/Resources/Bioethical%20Issues.html></ref>
Maintaining good practices in CVS testing and any other prenatal testing is essential to exercise the duty of care and to reduce any sort of harm upon the expectant mother. CVS:

*Should not be performed under 10 weeks gestation.
*Should be performed by an experienced, well trained technician
*Written consent should be obtained before testing
*Clinicians should use the CVS technique with which they are competent, using local anaesthesia for transabdominal CVS.
<ref>Royal Collage of Obstetricians and Gynaecologyists. 2010. Green-top Guideline No. 8 Amniocentesis and Chorionic Villus Sampling. Accessed 6 October, 2010. <http://www.rcog.org.uk/files/rcog-corp/GT8Amniocentesis0610.pdf></ref>

[[File:AbortionLawMap.png|thumb|right|200px|A World Map showing the legal status of abortion in different countries. Enlarge for legend.]]
'''Abortion'''

Abortion is a subject that brings about a wide number of ethical concerns whether morally, religiously and politically around the world.
Usually a community's beliefs and moral views are reflected in political decisions, although debate continues to be ongoing whether it is morally right to terminate a pregnancy before a normal childbirth, given a range of different circumstances people believe is acceptable. In Australia, abortion laws are present and differ by state, and is usually based on the mother's choice, given that she conforms to the restrictions of the law.

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling and Prenatal diagnosis techniques=

[[File:FISH_(technique).gif‎|thumb|250 px|FISH technique]]

[[File:Comparative_Genomics.jpg|thumb|250 px|Comparative Genomics]]

Prenatal diagnosis has been used to detect chromosomal abnormalities, especially Down’s syndrome, for over 30 years. As we have discussed on this page, the most common forms of prenatal diagnosis are amniocentesis, CVS and ultrasound. The type of test used depends on the history of the parents, any abnormalities detected in the initial ultrasound examination, and preferences of the parents. Testing for chromosomal abnormalities using amniocentesis and CVS is invasive and somewhat time consuming. Some recent advancements in this field include the use of fluorescence in situ hybridisation (FISH), quantitative fluorescence-PCR techniques, and comparative genomics. Although these techniques are currently still invasive, the waiting time for these tests is usually only 1 to 2 days for chromosomal abnormalities. <ref><pubmed>20014413</pubmed></ref> This waiting time would mean a much less stressful waiting period for the parents. The future of prenatal diagnosis certainly lies in the field of non invasive techniques, and research in the field of prenatal diagnosis is looking toward making detection of abnormalities non invasive, using the fetal cells from maternal circulation. <ref><pubmed>20014413</pubmed></ref>

'''Fluorescence in situ hybridisation (FISH):''' FISH is a cytogenetic technique, involving analysing the number and shape of the chromosomes of cells. FISH detects the addition or deletion of specific DNA sequences on chromosomes using florescent probes that bind to a similar sequence of chromosomes. Once the florescence probes are attached, fluorescence microscopy is used to view the chromosomes and detect the abnormality. In prenatal diagnosis, FISH is useful for detecting trisomy and monosomy conditions.[http://en.wikipedia.org/wiki/Fluorescent_in_situ_hybridization More about FISH]

'''Comparative genomics:''' Comparative Genomics is a very new research field where the genome sequence of different organisms are compared. This comparison between organisms shows where a species genomes have been conserved (stabilising selection) and where differences occur (positive selection). Many species share the same genes, and comparative genomics can show what species share genes and which genes are different among species. This information can help us understand the function of different genes and identify and control diseases. The purpose is to gain a better understanding of how species have evolved and to determine the function of genes. In prenatal diagnosis, fetal cells can be viewed and compared against both parents genome, any change that deviates from the normal pattern due to too much or too little DNA can be seen, this deviation of the normal pattern means a certain chromosome has either been copied or deleted, causing disease. [http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml More about Comparative Genomics]

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-10-06T13:45:11Z

Z3224500: /* Outcomes */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=
[[File:Gray37.png|right|thumb|280px|Sample is taken from the chorionic villi]]
[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. Between 10-12 weeks of pregnancy, the developing gestational sac is composed of a thick, outer chorionic membrane surrounding the amniotic cavity, a thin amniotic membrane and the chorionic cavity. The chorionic villi have now degenerated over most of the outer membrane, forming the chorion laeve, and the remaining villi fuses and embeds loosely into the decidua basalis. This forms the chorion frondosum, which will ultimately become the placenta. At this stage, the villi float freely in the blood of the intervillus space. Each villi is branched, and is composed of an outer syncytiotrophoblast and an inner cytotrophoblast layer. Within the centre of each villus is a mesenchymal core which contain capillaries carrying fetal blood. In CVS, usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.<ref>Jenkins, T.M, Wapner, R.J, 1999. First trimester prenatal diagnosis: Chorionic villus sampling. Seminars in Perinatology. pp403-413.</ref>

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. Women who had transcervical sampling had higher occurrence of fluid leakage and spotting. When a tenaculum is not used, the occurrence of vaginal spotting and bleeding continued. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory, which is a laboratory that analyses the number and shape of the chromosomes in cells. At the laboratory the cells are cultured (stimulated to grow and divide) for approximately 12 days. After enough cells are cultured, a banded karyotype is completed. This is where the fetal chromosomes in the cultured cells are stained and then photographed. The photographed chromosomes are then ordered, counted and checked for abnormalities.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.
[[file:suctionaspiration.png|thumb|right|200px|Suction Aspiration technique. Enlarge for labels.]]
Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors.<ref>Cica. N., 1998. Abortion Law in Australia. Parliament of Australia, Parliamentary Library. Accessed September 29. 2010. <http://www.aph.gov.au/library/pubs/rp/1998-99/99rp01.htm></ref> If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems.<ref>Medline Plus: Trusted Health Information for You. 2010. Down's Syndrome. Accessed Septemeber 28, 2010.<http://www.nlm.nih.gov/medlineplus/ency/article/000997.htm></ref> Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.<ref>Roizen, N., Patterson, D., 2003. Down's syndrome. The Lancet. 361:1281-1289</ref>

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

'''Bioethics'''

The Bioethics involved in Health Care that encompasses medical practices including prenatal diagnosis methods aim to ensure that human values are respected in terms of healthcare institutions, life technology, health professions and clinical practices.<ref>Southern Cross Bioethics Institute. 2008. Bioethical Issues. Accessed 6 October, 2010. <http://www.bioethics.org.au/Resources/Bioethical%20Issues.html></ref>
Maintaining good practices in CVS testing and any other prenatal testing is essential to exercise the duty of care and to reduce any sort of harm upon the expectant mother. CVS:

*Should not be performed under 10 weeks gestation.
*Should be performed by an experienced, well trained technician
*Written consent should be obtained before testing
*Clinicians should use the CVS technique with which they are competent, using local anaesthesia for transabdominal CVS.
<ref>Royal Collage of Obstetricians and Gynaecologyists. 2010. Green-top Guideline No. 8 Amniocentesis and Chorionic Villus Sampling. Accessed 6 October, 2010. <http://www.rcog.org.uk/files/rcog-corp/GT8Amniocentesis0610.pdf></ref>

[[File:AbortionLawMap.png|thumb|right|200px|A World Map showing the legal status of abortion in different countries. Enlarge for legend.]]
'''Abortion'''

Abortion is a subject that brings about a wide number of ethical concerns whether morally, religiously and politically around the world.
Usually a community's beliefs and moral views are reflected in political decisions, although debate continues to be ongoing whether it is morally right to terminate a pregnancy before a normal childbirth, given a range of different circumstances people believe is acceptable. In Australia, abortion laws are present and differ by state, and is usually based on the mother's choice, given that she conforms to the restrictions of the law.

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling and Prenatal diagnosis techniques=

[[File:FISH_(technique).gif‎|thumb|250 px|FISH technique]]

[[File:Comparative_Genomics.jpg|thumb|250 px|Comparative Genomics]]

Prenatal diagnosis has been used to detect chromosomal abnormalities, especially Down’s syndrome, for over 30 years. As we have discussed on this page, the most common forms of prenatal diagnosis are amniocentesis, CVS and ultrasound. The type of test used depends on the history of the parents, any abnormalities detected in the initial ultrasound examination, and preferences of the parents. Testing for chromosomal abnormalities using amniocentesis and CVS is invasive and somewhat time consuming. Some recent advancements in this field include the use of fluorescence in situ hybridisation (FISH), quantitative fluorescence-PCR techniques, and comparative genomics. Although these techniques are currently still invasive, the waiting time for these tests is usually only 1 to 2 days for chromosomal abnormalities. <ref><pubmed>20014413</pubmed></ref> This waiting time would mean a much less stressful waiting period for the parents. The future of prenatal diagnosis certainly lies in the field of non invasive techniques, and research in the field of prenatal diagnosis is looking toward making detection of abnormalities non invasive, using the fetal cells from maternal circulation. <ref><pubmed>20014413</pubmed></ref>

'''Fluorescence in situ hybridisation (FISH):''' FISH is a cytogenetic technique, involving analysing the number and shape of the chromosomes of cells. FISH detects the addition or deletion of specific DNA sequences on chromosomes using florescent probes that bind to a similar sequence of chromosomes. Once the florescence probes are attached, fluorescence microscopy is used to view the chromosomes and detect the abnormality. In prenatal diagnosis, FISH is useful for detecting trisomy and monosomy conditions.[http://en.wikipedia.org/wiki/Fluorescent_in_situ_hybridization More about FISH]

'''Comparative genomics:''' Comparative Genomics is a very new research field where the genome sequence of different organisms are compared. This comparison between organisms shows where a species genomes have been conserved (stabilising selection) and where differences occur (positive selection). Many species share the same genes, and comparative genomics can show what species share genes and which genes are different among species. This information can help us understand the function of different genes and identify and control diseases. The purpose is to gain a better understanding of how species have evolved and to determine the function of genes. In prenatal diagnosis, fetal cells can be viewed and compared against both parents genome, any change that deviates from the normal pattern due to too much or too little DNA can be seen, this deviation of the normal pattern means a certain chromosome has either been copied or deleted, causing disease. [http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml More about Comparative Genomics]

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-10-06T13:30:02Z

Z3224500: /* Outcomes */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=
[[File:Gray37.png|right|thumb|280px|Sample is taken from the chorionic villi]]
[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. Between 10-12 weeks of pregnancy, the developing gestational sac is composed of a thick, outer chorionic membrane surrounding the amniotic cavity, a thin amniotic membrane and the chorionic cavity. The chorionic villi have now degenerated over most of the outer membrane, forming the chorion laeve, and the remaining villi fuses and embeds loosely into the decidua basalis. This forms the chorion frondosum, which will ultimately become the placenta. At this stage, the villi float freely in the blood of the intervillus space. Each villi is branched, and is composed of an outer syncytiotrophoblast and an inner cytotrophoblast layer. Within the centre of each villus is a mesenchymal core which contain capillaries carrying fetal blood. In CVS, usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.<ref>Jenkins, T.M, Wapner, R.J, 1999. First trimester prenatal diagnosis: Chorionic villus sampling. Seminars in Perinatology. pp403-413.</ref>

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. Women who had transcervical sampling had higher occurrence of fluid leakage and spotting. When a tenaculum is not used, the occurrence of vaginal spotting and bleeding continued. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory, which is a laboratory that analyses the number and shape of the chromosomes in cells. At the laboratory the cells are cultured (stimulated to grow and divide) for approximately 12 days. After enough cells are cultured, a banded karyotype is completed. This is where the fetal chromosomes in the cultured cells are stained and then photographed. The photographed chromosomes are then ordered, counted and checked for abnormalities.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.
[[file:suctionaspiration.png|thumb|right|200px|Suction Aspiration technique. Enlarge for labels.]]
Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors.<ref>Cica. N., 1998. Abortion Law in Australia. Parliament of Australia, Parliamentary Library. Accessed September 29. 2010. <http://www.aph.gov.au/library/pubs/rp/1998-99/99rp01.htm></ref> If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

'''Bioethics'''

The Bioethics involved in Health Care that encompasses medical practices including prenatal diagnosis methods aim to ensure that human values are respected in terms of healthcare institutions, life technology, health professions and clinical practices.<ref>Southern Cross Bioethics Institute. 2008. Bioethical Issues. Accessed 6 October, 2010. <http://www.bioethics.org.au/Resources/Bioethical%20Issues.html></ref>
Maintaining good practices in CVS testing and any other prenatal testing is essential to exercise the duty of care and to reduce any sort of harm upon the expectant mother. CVS:

*Should not be performed under 10 weeks gestation.
*Should be performed by an experienced, well trained technician
*Written consent should be obtained before testing
*Clinicians should use the CVS technique with which they are competent, using local anaesthesia for transabdominal CVS.
<ref>Royal Collage of Obstetricians and Gynaecologyists. 2010. Green-top Guideline No. 8 Amniocentesis and Chorionic Villus Sampling. Accessed 6 October, 2010. <http://www.rcog.org.uk/files/rcog-corp/GT8Amniocentesis0610.pdf></ref>

[[File:AbortionLawMap.png|thumb|right|200px|A World Map showing the legal status of abortion in different countries. Enlarge for legend.]]
'''Abortion'''

Abortion is a subject that brings about a wide number of ethical concerns whether morally, religiously and politically around the world.
Usually a community's beliefs and moral views are reflected in political decisions, although debate continues to be ongoing whether it is morally right to terminate a pregnancy before a normal childbirth, given a range of different circumstances people believe is acceptable. In Australia, abortion laws are present and differ by state, and is usually based on the mother's choice, given that she conforms to the restrictions of the law.

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling and Prenatal diagnosis techniques=

[[File:FISH_(technique).gif‎|thumb|250 px|FISH technique]]

[[File:Comparative_Genomics.jpg|thumb|250 px|Comparative Genomics]]

Prenatal diagnosis has been used to detect chromosomal abnormalities, especially Down’s syndrome, for over 30 years. As we have discussed on this page, the most common forms of prenatal diagnosis are amniocentesis, CVS and ultrasound. The type of test used depends on the history of the parents, any abnormalities detected in the initial ultrasound examination, and preferences of the parents. Testing for chromosomal abnormalities using amniocentesis and CVS is invasive and somewhat time consuming. Some recent advancements in this field include the use of fluorescence in situ hybridisation (FISH), quantitative fluorescence-PCR techniques, and comparative genomics. Although these techniques are currently still invasive, the waiting time for these tests is usually only 1 to 2 days for chromosomal abnormalities. <ref><pubmed>20014413</pubmed></ref> This waiting time would mean a much less stressful waiting period for the parents. The future of prenatal diagnosis certainly lies in the field of non invasive techniques, and research in the field of prenatal diagnosis is looking toward making detection of abnormalities non invasive, using the fetal cells from maternal circulation. <ref><pubmed>20014413</pubmed></ref>

'''Fluorescence in situ hybridisation (FISH):''' FISH is a cytogenetic technique, involving analysing the number and shape of the chromosomes of cells. FISH detects the addition or deletion of specific DNA sequences on chromosomes using florescent probes that bind to a similar sequence of chromosomes. Once the florescence probes are attached, fluorescence microscopy is used to view the chromosomes and detect the abnormality. In prenatal diagnosis, FISH is useful for detecting trisomy and monosomy conditions.[http://en.wikipedia.org/wiki/Fluorescent_in_situ_hybridization More about FISH]

'''Comparative genomics:''' Comparative Genomics is a very new research field where the genome sequence of different organisms are compared. This comparison between organisms shows where a species genomes have been conserved (stabilising selection) and where differences occur (positive selection). Many species share the same genes, and comparative genomics can show what species share genes and which genes are different among species. This information can help us understand the function of different genes and identify and control diseases. The purpose is to gain a better understanding of how species have evolved and to determine the function of genes. In prenatal diagnosis, fetal cells can be viewed and compared against both parents genome, any change that deviates from the normal pattern due to too much or too little DNA can be seen, this deviation of the normal pattern means a certain chromosome has either been copied or deleted, causing disease. [http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml More about Comparative Genomics]

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

File:Suctionaspiration.png

2010-10-06T13:25:38Z

Z3224500: =Labels= 1. Amniotic sac 2. Embryo 3. Uterine lining 4. Speculum 5. Vacurette 6.The vacurette is attached to a suction pump Copyright Information: This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. " You

User:Z3224500

2010-10-06T12:27:14Z

Z3224500:

Talk:2010 Group Project 2

2010-10-06T12:11:01Z

Z3224500:

Hey I've completed the ethics section... Hope it's acceptable, I feel it's a little tacky, since I didn't want to go very much in detail with Bioethics and Abortion issues because I thought it might be a little off track..--[[User:Z3224500|Jenny Huang]] 12:11, 6 October 2010 (UTC)

yes our page looks very good :D ohhh sorry for the delay on the ethics part.. I had 2 assignments that were due just the other day... no worries I'll be done by tonight :D--[[User:Z3224500|Jenny Huang]] 06:33, 6 October 2010 (UTC)

LOVE our page!!! looks awesome! i think we have done everything we can to get maximum marks, and i have learnt heaps doing it! Dont forget Mark is locking the page at some stage as its due tomorrow (i think he will prob lock them tomorrow morning or something). If you need help with any of your sections let me know, i have finished my bits :D yay!! --[[User:Z3265772|z3265772]] 04:50, 6 October 2010 (UTC)

Umm.. I'm not sure about that, because the sources I found mosaicism on had it in their "limitations" heading... --[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)--[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)

Hey Jenny, do you think Mosaicism should be in the abnormalities found by CVS section? a few people have commented that its a bit confusing what the test detects and the risks associated with testing. i think Mosaicism is more under the heading of what cvs detects --[[User:Z3265772|z3265772]] 04:16, 23 September 2010 (UTC)

hey jill,
group 6 here, you may use our picture

--[[User:Z3254433|z3254433]] 09:07, 26 September 2010 (UTC)

===to fix===

'''Begin''' by collating the comments.
* What are the common criticisms?
* What were the best aspects identified within your project?
* What errors, typos, missing references were identified?
* Were there contributions from individual group members that were identified as good or poor parts of the overall project?

'''Then''' work on the changes.
* Develop priorities.
* Divide the changes and corrections between group members.
* Are there additional changes that should be made that were not identified by peer assessment.

'''Jill:'''

DONE abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? comparative genomics, Improvements?

DONE future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether

DONE move glossary above references so you dont have to scroll all the way down to read them

DONE table comparing other techniques

DONE got confused between the risks of this test and what it predicted (this will be clear in the above table)

DONE -it didn't state that the test was invasive in intro (table)

DONE -All spelling amd grammar - some more editing of spelling is required

DONE "abnormalities found by CVS" section towards the top of the page coz I got confused between the risks of this test and what it predicted

DONE -link or a reference to the brief time line where you state the names of the authors

DONE -The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed

DONE -I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources

DONE -a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work

DONE - it would be that you put the advantages/disadvantages of CVS over other techniques in a table.

'''Jenny:'''

DONE flowchart or more pictures of procedure (not sure how to do a flow chart, haven't got any ideas on doing this =S)

DONE clarify what hypertension is in the hypertensive disorders of pregnancy section

DONEoutcomes + ethics,

DONE Are the transabdominal and the transcervical pictures the student-drawn ones? put up in discussion that you drew them and you give permission for re-use - Jenny, ive done this for you, all you need to do is edit and add your student number, -Jill

DONE elaborate on procedure eg what cells are being taken etc and stages of chorionic villus in embryology

DONE Spelling and grammar, - Jenny, ive gone through the page and edited the spelling mistakes i could find, could you please do the same incase ive missed any? and double check the sections you are about to write? Thanks :) - Jill --[[User:Z3265772|z3265772]] 00:33, 24 September 2010 (UTC)

[leave as is] The current research section could be put more into point form to make it more inviting to read - not sure if you want to do this, i think its ok as it is, maybe just delete this suggestion? or add pictures of people researching? haha

----

==Peer Review==

'''Please note!''' when posting your peer review, we only have two group members. the other one dropped out. Thanks :)

--[[User:Z3129413]] 16:29, 22 September 2010 (UTC)
I love those old timey pencil medical pictures and so for me this was really great, what instantly nailed the whole positive immediate impression was 'Reasons for getting chorionic villus sampling etc etc' right there at the beginning. Why would I get one? thanks very much. Perhaps a darker font would make it even better. Historical back ground is really good and technique pictures are of high standard. The table presentation of abnormalities found and ratios is such an effective way of portraying this information.

A few Q's with the hypertension cvs topic,
Is there a normally expected percent of women in a large population to develop hypertensive disorders, just for perspective? CVS would not lower incidences of such surely (9098 pop, 2.7% to 7.1% control). 138 study size seems a bit low, is result really much more significant? However I did understand that CVS was more risk prone than amniocentesis for pre eclampsia and gestational hypertension.
This project is well on track.

Group 2: Your project is very impressive in content as well as organisation. The most notable thing for me was the wide use of pictures which must have taken a lot of time and effort to source. They definitely create an engaging page especially in conjunction with the use of tables and clear subheadings. The structure you have used is very effective as it allows your information to be scientific and thorough but at the same time it is concise and easy to navigate. I felt like i got an extensive overview of CVS after having read your page and the use of pictures and subheadings kept it from being a chore. I felt the history and abnormalities sections were particularly interesting. I also appreciate how you have seemed to approach this topic from all angles and not just a one-sided, all current and positive viewpoint. To improve your page perhaps you could explore the future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether. Either way your page is probably up to standard as it is and it is obvious that you have worked hard at it. Job well done.
--[[User:Z3293029|z3293029]] 14:38, 22 September 2010 (UTC)

Group 2: fantastic use of images, it definitely worked to your advantage in engaging your audience's attention. Over all the language used is relatively easy to follow yet informative. As someone has already mentioned, some more editing of spelling is required. The amount of attention to detail is evident in the references which are from a range of sources so well done. I particularly liked that the page covered accuracy and limitations of the diagnostic procedure. Something that lacked clarity in a few other groups. Good use of the table covering the abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? Improvements?
Just an idea. Well done overall. --z3241780 13:40, 22 September 2010 (UTC)

'''GROUP 2: Chorionic Villi Sampling'''

This page caught my attention as soon as I saw it and that made me want to read on and thus learn about Chorionic Villi Sampling. A lot of research has gone into this assignment and it’s evident in the information presented as its precise which also helps capture the readers. The amount of research is also evident in the long list of references. The webpage is actually extremely informative covering pretty much every aspect of the pre-natal diagnostic techniques. Your webpage has the most pictures and this helps it stand out as one of the best project pages. I really, really like the formatting and the tables. The images break up the information so you’re never overloaded with the amount of text. The only bit of criticism is spelling but this is extremely minor as you’ll pick up on the spelling mistakes when you go over the page. The language in is the right mixture of scientific language meaning that even people without a scientific background can understand the CVS. Great job guys you really can’t tell that only two people are in this group. It’s extremely good!!! I also really like the first picture you have, gives a page a really good feel to it.

--[[User:Z3252635|z3252635]] 13:20, 22 September 2010 (UTC)

Hi guys!

You have found so many great pictures! Your page looks amazing. I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources. Your timeline was great too; I really like how you put up the concise timeline and then expanded a bit on the major developments afterwards. Are the transabdominal and the transcervical pictures the student-drawn ones? If so, well done! They’re really clear and beautifully done, but you should probably label them as student drawn and put in the copyright statement. If I could suggest something, it would be that you put the advantages/disadvantages of CVS over other techniques in a table. Otherwise, your page is really easy to read, and again has brilliant visuals – great job!--[[User:Z3252833|z3252833]] 12:42, 22 September 2010 (UTC)

CVS.

Group 2, your project is looking great, the first thing i noticed when reading it is that there is lots of detail which shows a great depth of research has gone into it, which is supported by your reference list. Another thing is the amount of pictures which support the information and break it up to make it easier to take in so much information at once. The disorders table provides great detail and makes it interesting with the pictures.

What could be improved: You could put the advantages/disadvantages into a table form to make it even easier to understand. The reasons to use this technique could be slotted into the procedure section instead of the introduction maybe as it shows who is eligible for the procedure. The current research section could be put more into point form to make it more inviting to read. But overall really great project.

--[[User:Z3292208|z3292208]] 08:55, 22 September 2010 (UTC)

This project is extremely well done. It seems a great effort has gone into proper referencing which also gives the impression of a thoughtful attempt. The balance of information mediums is great and the logical flow of ideas when reading through each section is perfect.
Suggestion: possibly more pictures or a flowchart of the procedure itself?

Well done :)

--[[User:Z3254753|z3254753]] 16:55, 21 September 2010 (UTC)

Group 2- This project had tons of photos which is super great because its much easier to follow... Most of the point made is supported with pictures ..definetly provided me a better understanding of CVS ..I agree with what others have mentioned its very informative and especially with just 2 team members .. fantastic work

what could be improved = a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work ..--[[User:Z3305561|Navneet Ahuja]] 12:53, 21 September 2010 (UTC)

Group project 2: chorionic villus sampling

This group had great images and the page layout was good too especially the tables which simplified the information and made it easier to read. The information presented was very informative, scientific, and all the key concepts were covered on the topic. The project had a very impressive reference list, and it did help in my understanding of this prenatal diagnostic technique.

What could be improved?
I did find a spelling mistake under the heading Results and Accuracy were you have written “maybe” instead of “baby”, so maybe proof read the assignment to pick up on any other possible spelling or grammatical errors, other than that well done.

--[[User:Z3254433|z3254433]] 07:15, 20 September 2010 (UTC)

This project was highly informative about CVS. It contained a lot of information in which it shows that a lot of research has gone into it. Everything has been covered like, what the test predicts and what risks are associated with this test. It was very scientific, yet easy to understand at a non-scientific level. I liked the external links how it directed me straight to a page of different articles about CVS.

What could be improved is maybe placing the "abnormalities found by CVS" section towards the top of the page, because i was a bit unsure on what this test predicted in the first place. I got confused between the risks of this test and what it predicted. But I managed to understand it all once all read through. Also, a definition of a "cannula" may be helpful in the glossary too, i wasn't sure what that exactly was.

--[[User:Z3291079|z3291079]] 02:48, 21 September 2010 (UTC)

This project provides a clear understanding of the key information regarding CVS, such as how it is carried out, the risks and benfits of CVS, what it is used for as well as future research. I have find the pictures to be of a great help in explaining the procedure of CVS.

One think I did notice was that, it didn't state that the test was invasive until you figure it out when you look at the pictures in the procedures. I think stating that in the introduction would make it clearer for readers to follow on with the information this projects provides having that knowledge in mind at the start.

--[[User:Z3216889|3216889]] 12:13, 22 September 2010 (UTC)

This web page is definitely one of my favorites. The information that you have provided is exceptional; the reference list is indicative of your extensive research. The table of deformities was a stand out for me as it was very well set out and was a effective break from the text. You also used excellent external links that were very well placed within the web page. A slight improvement would be to include a link or a reference to the brief time line where you state the names of the authors, and as previously mentioned, reference the statistics that you have included. Other than that, I applaud you for a job well done!--[[User:Z3252083|z3252083]] 12:22, 22 September 2010 (UTC)

--Group 2 Chronic villus sampling
This webpage shows that the group was very thorough in the research due to the amount of detail that has gone into it and its many links. The layout is very well set out which helps someone understand it if he/she has no previous knowledge of the concept. The use of pictures and diagrams were done well as it broke the page up making it very easy to read and take in the information. The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed. That’s all guys and well done considering you only had 2 people working on it.

--[[User:Z3290040|3290040]] 10:19, 22 September 2010 (UTC)

----

----

===group discussion===

I agree the page feels more "in order" now. yeh... its tough trying to find more information. I guess i'll expand on maybe on some of the abnormalities? I was thinking we can get pictures of the several diseases but it will probably be a little difficult due to copyright? hmm if i get new ideas from now until tommorrow i'll definately add more stuff in --[[User:Z3224500|Jenny Huang]] 06:38, 15 September 2010 (UTC)

Hey Jenny, i changed the order of the page around, i think it makes more sense now, before it didnt really flow from one section to the next, i think its a bit better, i tried to do it on this order, Intro, history, procedure, results, risks, advantages. that order seems to be how most wiki pages are set up, and how mark sets up his pages. what do you think? -Jill --[[User:Z3265772|z3265772]] 02:14, 15 September 2010 (UTC)

i think i searched prenatal diagnosis in the search box on the left, and mark has made a prenatal diagnosis page. the prenatal diagnosis terms were on that. ive been looking at last years pages, and they have so much content, but there just isnt that much information on CVS. theres only so much you can write about it. i guess we need to start thinking outside the box and adding general prenatal stuff on here too. thats why i thought maybe another table with a timeline of other techniques on it. ? ill just do it and see how it looks... -Jill --[[User:Z3265772|z3265772]] 01:47, 15 September 2010 (UTC)

hmm good idea.. btw what article did you find the terms for the prenatal diagnosis? should i incorporate that in the results section? --[[User:Z3224500|Jenny Huang]] 15:19, 14 September 2010 (UTC)

maybe we could also do ethical issues? -Jill --[[User:Z3265772|z3265772]] 12:35, 14 September 2010 (UTC)

Just an idea if we wanted to add more to the page, we could do another table, with the different diagnostic techniques used - eg ultrasound, AFP, amniocentesis and CVS etc and do a timeline with when each technique can be used, what it can test for, and how invasive it is. i know its not directly CVS, but it will give a good overview of the advantages and disadvantages etc. and im running out of ideas of what else we can have on here. can you think of anything else? -Jill --[[User:Z3265772|z3265772]] 12:30, 14 September 2010 (UTC)

Found out its due thurs, Sorry!! im doing malformations now, but we definitely need to add more content, last years pages had over 600 revisions, we only have 200. So add whatever you think we could do to improve the page. Thanks for your help over the weekend, i did feel alone in creating the page! Looks great now though! Maybe we could look at last years pages and see what we like about them, and maybe get some ideas on how to add to our page. im trying to put alot of effort in as its worth 20% of our final mark :) ive also added to the malformations part, ill keep doing that. Thanks!! -Jill --[[User:Z3265772|z3265772]] 02:24, 13 September 2010 (UTC)

Hey can't make it to lecture today.. but if its due for peer assesment today/this week, what suggestions do you think we can improve on? hmm also whos doing the part on malformations? --[[User:Z3224500|Jenny Huang]] 23:07, 12 September 2010 (UTC)

yeah good question.. ill see if i can find something more recent and let you know. i guess it would be. also, hope you dont mind, i put some of your references in, and added some pictures :) -Jill --[[User:Z3265772|z3265772]] 13:00, 12 September 2010 (UTC)

Hey for the section on malformations in current research, would it be limb defects? the articles I found were mostly from the 1990s so I'm not sure if I should use..--[[User:Z3224500|Jenny Huang]] 12:49, 12 September 2010 (UTC)

Yay it looks neat!!!glad you figured out how to fix the formatting.. It was rather confusing before haha. SOrry if it seems like you are doing most of the work :( I'll add to the current research to lighten off your load.i'll be working on it most of the weekend--[[User:Z3224500|Jenny Huang]] 16:39, 10 September 2010 (UTC)

I made a table!! it took AGES but it looks good :) we probably need to spread everything out a bit, it looks a bit crowded, but getting there! i separated the risks from current research :)- Jill --[[User:Z3265772|z3265772]] 12:03, 10 September 2010 (UTC)

Hmm it didn't take that long.. btw I've already done it but I haven't uploaded it yet but I'll do so now... hmm by the way should the heading "risks" be separate from the "current assosciated research" heading?--[[User:Z3224500|Jenny Huang]] 02:53, 10 September 2010 (UTC)

Hey! Did it take long to do the drawing for the transabdominal technique? i was thinking we could do a second one the same for transcervical. what do you think? - Jill --[[User:Z3265772|z3265772]] 02:09, 10 September 2010 (UTC)

Im pretty sure its due monday for peer assessment, thats what it says in the course guide. did he say it was due thurs in the lab last week? hope its due thurs! that would be awesome! - Jill --[[User:Z3265772|z3265772]] 12:00, 9 September 2010 (UTC)

Hey Jill, wow only 4 days! I was mistaken that it was due next thursday. But don't wrry, I'll have the whole weekend to finish up ;)--[[User:Z3224500|Jenny Huang]] 08:30, 9 September 2010 (UTC)

Hi! Ive used a reference that is not from pub med, so you can copy that to use references that arent in pub med. :) only 4 days till its due! - Jill --[[User:Z3265772|z3265772]] 01:29, 9 September 2010 (UTC)

some pictures we can use, this first one is Primary chorionic villi, the second picture is secondary chorionic villi, these may be helpful when describing the technique -Jill --[[User:Z3265772|z3265772]] 09:52, 7 September 2010 (UTC)

[[File:Gray36.png|left|400 px]]

[[File:Gray37.png|left|400 px]]

Hmm so basically we do the peer review the week after mid sem break until the 23rd of september, and we paste both the review on the groups page and on your own page... also apparently the other student discontinued the course so its just us doing the project now =S --[[User:Z3224500|Jenny Huang]] 03:02, 2 September 2010 (UTC)

Yay!! looks awesome!! Sorry i couldnt be there today, could you let me know what Mark says? thanks :) - Jill --[[User:Z3265772|z3265772]] 23:59, 1 September 2010 (UTC)

I've uploaded the first pic... I hope it's ok and if I did the layers wrongly please tell me so I can edit... also how do you do referencing that is not from pubmed journals?--[[User:Z3224500|Jenny]] 23:18, 1 September 2010 (UTC)

Hi Jenny, are you doing the drawn figure still? would you possibly be able to upload it before thursday? i have updated references for my section :) - Jill --[[User:Z3265772|z3265772]] 08:52, 1 September 2010 (UTC)

--[[User:S8600021|Mark Hill]] 00:49, 31 August 2010 (UTC) I have emailed your missing team member , but have not had a response yet. Your should continue to work on the project together as best you can. It seems to be progressing, though I did ask you to update your reference format and I do not see a student drawn figure. You need to have this updated before this weeks lab when I will be reviewing all projects.

Hi Jill, I'm working on it :) by the way have you heard from the other team member? Oh and I'll be drawing pictures for both the transcervical and transabdominal techniques..--[[User:Z3224500|Jenny Huang]] 07:46, 30 August 2010 (UTC)

Hi guys, only two weeks to go, we really need to do some more work, the editing at the end will be the hardest, so the sooner we finish, the easier it will be. - Jill--[[User:Z3265772|z3265772]] 23:46, 29 August 2010 (UTC)

Can we incorporate some sort of timeline? what do you think? maybe we can do a timeline of embryo development and note the time that CVS is done - Jill --[[User:Z3265772|z3265772]] 00:57, 26 August 2010 (UTC)

Mark has kindly shown us how to reference, ill try to sort that out tonight or tomorrow - Jill --[[User:Z3265772|z3265772]] 23:16, 25 August 2010 (UTC)

Ive just discovered, you can use almost any picture on wiki, the copyrights have usually expired, which is why wiki can use them, just search CVS on wiki and if there is a picture you like, check the copyright and copy away!! :D -Jill --[[User:Z3265772|z3265772]] 01:05, 25 August 2010 (UTC)

Hi guys, please feel free to edit any work i have done, or add to it, or even suggest to me on this page what to add. what i have put up so far really is a rough draft and will be trying to add to it later anyway :) -Jill --[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

{{Template:Projects10MHtalk}}

Hi guys, we need to get on top of this, its due for peer assessment in 3 weeks! Im going to do related research. does anyone want to do the drawing? ill also try and get some more references and photos up, as Mark has suggested. If you want a picture, just email the website with the picture on it, thats what ive been doing, they are usually pretty good about it. let me know of any other ideas you guys might have - Jill --[[User:Z3265772|z3265772]] 09:50, 23 August 2010 (UTC)

--[[User:S8600021|Mark Hill]] 04:35, 23 August 2010 (UTC) OK there are a few references here, but you will need more than these few and there should be some related images.

Link for group assessment criteria: [[2010_Lab_1#Group_Assessment_Criteria|group assessment criteria]] - Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

For current associated research:

http://onlinelibrary.wiley.com/doi/10.1002/pd.2410/abstract

http://www.ncbi.nlm.nih.gov/pubmed/11263542

http://www.ncbi.nlm.nih.gov/pubmed/19683693

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T7V-4BWVXPY-F9&_user=10&_coverDate=03%2F31%2F1994&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1427646674&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a3c3f2d47ad01c562a3baea8c60a48bc

http://www.informaworld.com/smpp/content~db=all~content=a913951525

http://www.escardiocontent.org/periodicals/ejcpr/article/S0002-9378%2807%2900305-5/abstract

http://humrep.oxfordjournals.org/cgi/content/abstract/3/6/811

- Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

Hi guys, i put up the link for Search Pubmed for our topic, did we want to assign ourselves a role to do or just see how the page goes? i thought maybe we could find a page that we like and follow a similar format, that way we know what our page will look like and can follow a layout as we go. -Jill --[[User:Z3265772|z3265772]] 01:12, 9 August 2010 (UTC)

also, see this web page http://www.cdc.gov/mmwr/preview/mmwrhtml/00038393.htm Jill --[[User:Z3265772|z3265772]] 11:16, 9 August 2010 (UTC)

project outline:

1. Intro

2. historic background

3. current associated research

4. simplified description of technique

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

5. student drawn figure or animation

6. reference list

7. glossary

8. external links

-Jill --[[User:Z3265772|z3265772]] 03:05, 11 August 2010 (UTC)

Can anyone tell me how to paste a picture from an outside source? i cant seem to figure it out. thanks :)
-Jill --[[User:Z3265772|z3265772]] 05:03, 11 August 2010 (UTC)

dont worry, i figured it out :)

i think we should put the references list on this page to begin with to make sure we dont double up
- Jill --[[User:Z3265772|z3265772]] 05:31, 11 August 2010 (UTC)

Hey guys sorry for the delay in replies. I see you have made a contribution to the topic already :) By the way, where did you find the project outline criteria? Oh and if you don't mind I can do research on the description of technique and current research. Feel free to contribute :) oh and any ideas on how to work on the drawings? --[[User:Z3224500|Jenny Huang]] 15:29, 11 August 2010 (UTC)

Hello guys,

So I found some journal articles that is of interest especially this one: http://apps.who.int/rhl/reviews/langs/CD003252.pdf which is long and has extensive information on the topic..
So I'll be editing my section in word and will be posting some info on technique in the future.

Btw here are some other articles that are of interest that can be accessed through unsw sirius:

http://linkinghub.elsevier.com/retrieve/pii/S0889854505702916

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

http://journals.lww.com/co-obgyn/Abstract/2005/04000/Chorionic_villus_sampling_and_amniocentesis.16.aspx

Complications:

http://journals.lww.com/greenjournal/Abstract/2007/09000/Procedure_Related_Complications_of_Amniocentesis.24.aspx

http://journals.lww.com/greenjournal/Abstract/2008/10000/Evaluating_the_Rate_and_Risk_Factors_for_Fetal.12.aspx

I'll be adding more once I find some that are useful..

Oh and about the topic headings are we just going to use the ones in the assesment criteria?

--[[User:Z3224500|z3224500]] 15:03, 24 August 2010 (UTC)

Hey Jenny!! i think its a great idea to use more headings, add as many as you like/can think of, i just cant think of any more. i think the assessment criteria is just the bare minimum we have to do, so please add more! Also, can we add the new discussion posts to the top of the page? so we dont have to scroll to the bottom every time? what do you think? (it says up the top of this page to add newer material at the top, just wondering what you thought). i really like the articles you have found too :) see you tomorrow
- Jill --[[User:Z3265772|z3265772]] 00:29, 25 August 2010 (UTC)

Talk:2010 Group Project 2

2010-10-06T12:08:59Z

Z3224500:

yes our page looks very good :D ohhh sorry for the delay on the ethics part.. I had 2 assignments that were due just the other day... no worries I'll be done by tonight :D--[[User:Z3224500|Jenny Huang]] 06:33, 6 October 2010 (UTC)

LOVE our page!!! looks awesome! i think we have done everything we can to get maximum marks, and i have learnt heaps doing it! Dont forget Mark is locking the page at some stage as its due tomorrow (i think he will prob lock them tomorrow morning or something). If you need help with any of your sections let me know, i have finished my bits :D yay!! --[[User:Z3265772|z3265772]] 04:50, 6 October 2010 (UTC)

Umm.. I'm not sure about that, because the sources I found mosaicism on had it in their "limitations" heading... --[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)--[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)

Hey Jenny, do you think Mosaicism should be in the abnormalities found by CVS section? a few people have commented that its a bit confusing what the test detects and the risks associated with testing. i think Mosaicism is more under the heading of what cvs detects --[[User:Z3265772|z3265772]] 04:16, 23 September 2010 (UTC)

hey jill,
group 6 here, you may use our picture

--[[User:Z3254433|z3254433]] 09:07, 26 September 2010 (UTC)

===to fix===

'''Begin''' by collating the comments.
* What are the common criticisms?
* What were the best aspects identified within your project?
* What errors, typos, missing references were identified?
* Were there contributions from individual group members that were identified as good or poor parts of the overall project?

'''Then''' work on the changes.
* Develop priorities.
* Divide the changes and corrections between group members.
* Are there additional changes that should be made that were not identified by peer assessment.

'''Jill:'''

DONE abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? comparative genomics, Improvements?

DONE future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether

DONE move glossary above references so you dont have to scroll all the way down to read them

DONE table comparing other techniques

DONE got confused between the risks of this test and what it predicted (this will be clear in the above table)

DONE -it didn't state that the test was invasive in intro (table)

DONE -All spelling amd grammar - some more editing of spelling is required

DONE "abnormalities found by CVS" section towards the top of the page coz I got confused between the risks of this test and what it predicted

DONE -link or a reference to the brief time line where you state the names of the authors

DONE -The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed

DONE -I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources

DONE -a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work

DONE - it would be that you put the advantages/disadvantages of CVS over other techniques in a table.

'''Jenny:'''

DONE flowchart or more pictures of procedure (not sure how to do a flow chart, haven't got any ideas on doing this =S)

DONE clarify what hypertension is in the hypertensive disorders of pregnancy section

DONEoutcomes + ethics,

DONE Are the transabdominal and the transcervical pictures the student-drawn ones? put up in discussion that you drew them and you give permission for re-use - Jenny, ive done this for you, all you need to do is edit and add your student number, -Jill

DONE elaborate on procedure eg what cells are being taken etc and stages of chorionic villus in embryology

DONE Spelling and grammar, - Jenny, ive gone through the page and edited the spelling mistakes i could find, could you please do the same incase ive missed any? and double check the sections you are about to write? Thanks :) - Jill --[[User:Z3265772|z3265772]] 00:33, 24 September 2010 (UTC)

[leave as is] The current research section could be put more into point form to make it more inviting to read - not sure if you want to do this, i think its ok as it is, maybe just delete this suggestion? or add pictures of people researching? haha

----

==Peer Review==

'''Please note!''' when posting your peer review, we only have two group members. the other one dropped out. Thanks :)

--[[User:Z3129413]] 16:29, 22 September 2010 (UTC)
I love those old timey pencil medical pictures and so for me this was really great, what instantly nailed the whole positive immediate impression was 'Reasons for getting chorionic villus sampling etc etc' right there at the beginning. Why would I get one? thanks very much. Perhaps a darker font would make it even better. Historical back ground is really good and technique pictures are of high standard. The table presentation of abnormalities found and ratios is such an effective way of portraying this information.

A few Q's with the hypertension cvs topic,
Is there a normally expected percent of women in a large population to develop hypertensive disorders, just for perspective? CVS would not lower incidences of such surely (9098 pop, 2.7% to 7.1% control). 138 study size seems a bit low, is result really much more significant? However I did understand that CVS was more risk prone than amniocentesis for pre eclampsia and gestational hypertension.
This project is well on track.

Group 2: Your project is very impressive in content as well as organisation. The most notable thing for me was the wide use of pictures which must have taken a lot of time and effort to source. They definitely create an engaging page especially in conjunction with the use of tables and clear subheadings. The structure you have used is very effective as it allows your information to be scientific and thorough but at the same time it is concise and easy to navigate. I felt like i got an extensive overview of CVS after having read your page and the use of pictures and subheadings kept it from being a chore. I felt the history and abnormalities sections were particularly interesting. I also appreciate how you have seemed to approach this topic from all angles and not just a one-sided, all current and positive viewpoint. To improve your page perhaps you could explore the future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether. Either way your page is probably up to standard as it is and it is obvious that you have worked hard at it. Job well done.
--[[User:Z3293029|z3293029]] 14:38, 22 September 2010 (UTC)

Group 2: fantastic use of images, it definitely worked to your advantage in engaging your audience's attention. Over all the language used is relatively easy to follow yet informative. As someone has already mentioned, some more editing of spelling is required. The amount of attention to detail is evident in the references which are from a range of sources so well done. I particularly liked that the page covered accuracy and limitations of the diagnostic procedure. Something that lacked clarity in a few other groups. Good use of the table covering the abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? Improvements?
Just an idea. Well done overall. --z3241780 13:40, 22 September 2010 (UTC)

'''GROUP 2: Chorionic Villi Sampling'''

This page caught my attention as soon as I saw it and that made me want to read on and thus learn about Chorionic Villi Sampling. A lot of research has gone into this assignment and it’s evident in the information presented as its precise which also helps capture the readers. The amount of research is also evident in the long list of references. The webpage is actually extremely informative covering pretty much every aspect of the pre-natal diagnostic techniques. Your webpage has the most pictures and this helps it stand out as one of the best project pages. I really, really like the formatting and the tables. The images break up the information so you’re never overloaded with the amount of text. The only bit of criticism is spelling but this is extremely minor as you’ll pick up on the spelling mistakes when you go over the page. The language in is the right mixture of scientific language meaning that even people without a scientific background can understand the CVS. Great job guys you really can’t tell that only two people are in this group. It’s extremely good!!! I also really like the first picture you have, gives a page a really good feel to it.

--[[User:Z3252635|z3252635]] 13:20, 22 September 2010 (UTC)

Hi guys!

You have found so many great pictures! Your page looks amazing. I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources. Your timeline was great too; I really like how you put up the concise timeline and then expanded a bit on the major developments afterwards. Are the transabdominal and the transcervical pictures the student-drawn ones? If so, well done! They’re really clear and beautifully done, but you should probably label them as student drawn and put in the copyright statement. If I could suggest something, it would be that you put the advantages/disadvantages of CVS over other techniques in a table. Otherwise, your page is really easy to read, and again has brilliant visuals – great job!--[[User:Z3252833|z3252833]] 12:42, 22 September 2010 (UTC)

CVS.

Group 2, your project is looking great, the first thing i noticed when reading it is that there is lots of detail which shows a great depth of research has gone into it, which is supported by your reference list. Another thing is the amount of pictures which support the information and break it up to make it easier to take in so much information at once. The disorders table provides great detail and makes it interesting with the pictures.

What could be improved: You could put the advantages/disadvantages into a table form to make it even easier to understand. The reasons to use this technique could be slotted into the procedure section instead of the introduction maybe as it shows who is eligible for the procedure. The current research section could be put more into point form to make it more inviting to read. But overall really great project.

--[[User:Z3292208|z3292208]] 08:55, 22 September 2010 (UTC)

This project is extremely well done. It seems a great effort has gone into proper referencing which also gives the impression of a thoughtful attempt. The balance of information mediums is great and the logical flow of ideas when reading through each section is perfect.
Suggestion: possibly more pictures or a flowchart of the procedure itself?

Well done :)

--[[User:Z3254753|z3254753]] 16:55, 21 September 2010 (UTC)

Group 2- This project had tons of photos which is super great because its much easier to follow... Most of the point made is supported with pictures ..definetly provided me a better understanding of CVS ..I agree with what others have mentioned its very informative and especially with just 2 team members .. fantastic work

what could be improved = a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work ..--[[User:Z3305561|Navneet Ahuja]] 12:53, 21 September 2010 (UTC)

Group project 2: chorionic villus sampling

This group had great images and the page layout was good too especially the tables which simplified the information and made it easier to read. The information presented was very informative, scientific, and all the key concepts were covered on the topic. The project had a very impressive reference list, and it did help in my understanding of this prenatal diagnostic technique.

What could be improved?
I did find a spelling mistake under the heading Results and Accuracy were you have written “maybe” instead of “baby”, so maybe proof read the assignment to pick up on any other possible spelling or grammatical errors, other than that well done.

--[[User:Z3254433|z3254433]] 07:15, 20 September 2010 (UTC)

This project was highly informative about CVS. It contained a lot of information in which it shows that a lot of research has gone into it. Everything has been covered like, what the test predicts and what risks are associated with this test. It was very scientific, yet easy to understand at a non-scientific level. I liked the external links how it directed me straight to a page of different articles about CVS.

What could be improved is maybe placing the "abnormalities found by CVS" section towards the top of the page, because i was a bit unsure on what this test predicted in the first place. I got confused between the risks of this test and what it predicted. But I managed to understand it all once all read through. Also, a definition of a "cannula" may be helpful in the glossary too, i wasn't sure what that exactly was.

--[[User:Z3291079|z3291079]] 02:48, 21 September 2010 (UTC)

This project provides a clear understanding of the key information regarding CVS, such as how it is carried out, the risks and benfits of CVS, what it is used for as well as future research. I have find the pictures to be of a great help in explaining the procedure of CVS.

One think I did notice was that, it didn't state that the test was invasive until you figure it out when you look at the pictures in the procedures. I think stating that in the introduction would make it clearer for readers to follow on with the information this projects provides having that knowledge in mind at the start.

--[[User:Z3216889|3216889]] 12:13, 22 September 2010 (UTC)

This web page is definitely one of my favorites. The information that you have provided is exceptional; the reference list is indicative of your extensive research. The table of deformities was a stand out for me as it was very well set out and was a effective break from the text. You also used excellent external links that were very well placed within the web page. A slight improvement would be to include a link or a reference to the brief time line where you state the names of the authors, and as previously mentioned, reference the statistics that you have included. Other than that, I applaud you for a job well done!--[[User:Z3252083|z3252083]] 12:22, 22 September 2010 (UTC)

--Group 2 Chronic villus sampling
This webpage shows that the group was very thorough in the research due to the amount of detail that has gone into it and its many links. The layout is very well set out which helps someone understand it if he/she has no previous knowledge of the concept. The use of pictures and diagrams were done well as it broke the page up making it very easy to read and take in the information. The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed. That’s all guys and well done considering you only had 2 people working on it.

--[[User:Z3290040|3290040]] 10:19, 22 September 2010 (UTC)

----

----

===group discussion===

I agree the page feels more "in order" now. yeh... its tough trying to find more information. I guess i'll expand on maybe on some of the abnormalities? I was thinking we can get pictures of the several diseases but it will probably be a little difficult due to copyright? hmm if i get new ideas from now until tommorrow i'll definately add more stuff in --[[User:Z3224500|Jenny Huang]] 06:38, 15 September 2010 (UTC)

Hey Jenny, i changed the order of the page around, i think it makes more sense now, before it didnt really flow from one section to the next, i think its a bit better, i tried to do it on this order, Intro, history, procedure, results, risks, advantages. that order seems to be how most wiki pages are set up, and how mark sets up his pages. what do you think? -Jill --[[User:Z3265772|z3265772]] 02:14, 15 September 2010 (UTC)

i think i searched prenatal diagnosis in the search box on the left, and mark has made a prenatal diagnosis page. the prenatal diagnosis terms were on that. ive been looking at last years pages, and they have so much content, but there just isnt that much information on CVS. theres only so much you can write about it. i guess we need to start thinking outside the box and adding general prenatal stuff on here too. thats why i thought maybe another table with a timeline of other techniques on it. ? ill just do it and see how it looks... -Jill --[[User:Z3265772|z3265772]] 01:47, 15 September 2010 (UTC)

hmm good idea.. btw what article did you find the terms for the prenatal diagnosis? should i incorporate that in the results section? --[[User:Z3224500|Jenny Huang]] 15:19, 14 September 2010 (UTC)

maybe we could also do ethical issues? -Jill --[[User:Z3265772|z3265772]] 12:35, 14 September 2010 (UTC)

Just an idea if we wanted to add more to the page, we could do another table, with the different diagnostic techniques used - eg ultrasound, AFP, amniocentesis and CVS etc and do a timeline with when each technique can be used, what it can test for, and how invasive it is. i know its not directly CVS, but it will give a good overview of the advantages and disadvantages etc. and im running out of ideas of what else we can have on here. can you think of anything else? -Jill --[[User:Z3265772|z3265772]] 12:30, 14 September 2010 (UTC)

Found out its due thurs, Sorry!! im doing malformations now, but we definitely need to add more content, last years pages had over 600 revisions, we only have 200. So add whatever you think we could do to improve the page. Thanks for your help over the weekend, i did feel alone in creating the page! Looks great now though! Maybe we could look at last years pages and see what we like about them, and maybe get some ideas on how to add to our page. im trying to put alot of effort in as its worth 20% of our final mark :) ive also added to the malformations part, ill keep doing that. Thanks!! -Jill --[[User:Z3265772|z3265772]] 02:24, 13 September 2010 (UTC)

Hey can't make it to lecture today.. but if its due for peer assesment today/this week, what suggestions do you think we can improve on? hmm also whos doing the part on malformations? --[[User:Z3224500|Jenny Huang]] 23:07, 12 September 2010 (UTC)

yeah good question.. ill see if i can find something more recent and let you know. i guess it would be. also, hope you dont mind, i put some of your references in, and added some pictures :) -Jill --[[User:Z3265772|z3265772]] 13:00, 12 September 2010 (UTC)

Hey for the section on malformations in current research, would it be limb defects? the articles I found were mostly from the 1990s so I'm not sure if I should use..--[[User:Z3224500|Jenny Huang]] 12:49, 12 September 2010 (UTC)

Yay it looks neat!!!glad you figured out how to fix the formatting.. It was rather confusing before haha. SOrry if it seems like you are doing most of the work :( I'll add to the current research to lighten off your load.i'll be working on it most of the weekend--[[User:Z3224500|Jenny Huang]] 16:39, 10 September 2010 (UTC)

I made a table!! it took AGES but it looks good :) we probably need to spread everything out a bit, it looks a bit crowded, but getting there! i separated the risks from current research :)- Jill --[[User:Z3265772|z3265772]] 12:03, 10 September 2010 (UTC)

Hmm it didn't take that long.. btw I've already done it but I haven't uploaded it yet but I'll do so now... hmm by the way should the heading "risks" be separate from the "current assosciated research" heading?--[[User:Z3224500|Jenny Huang]] 02:53, 10 September 2010 (UTC)

Hey! Did it take long to do the drawing for the transabdominal technique? i was thinking we could do a second one the same for transcervical. what do you think? - Jill --[[User:Z3265772|z3265772]] 02:09, 10 September 2010 (UTC)

Im pretty sure its due monday for peer assessment, thats what it says in the course guide. did he say it was due thurs in the lab last week? hope its due thurs! that would be awesome! - Jill --[[User:Z3265772|z3265772]] 12:00, 9 September 2010 (UTC)

Hey Jill, wow only 4 days! I was mistaken that it was due next thursday. But don't wrry, I'll have the whole weekend to finish up ;)--[[User:Z3224500|Jenny Huang]] 08:30, 9 September 2010 (UTC)

Hi! Ive used a reference that is not from pub med, so you can copy that to use references that arent in pub med. :) only 4 days till its due! - Jill --[[User:Z3265772|z3265772]] 01:29, 9 September 2010 (UTC)

some pictures we can use, this first one is Primary chorionic villi, the second picture is secondary chorionic villi, these may be helpful when describing the technique -Jill --[[User:Z3265772|z3265772]] 09:52, 7 September 2010 (UTC)

[[File:Gray36.png|left|400 px]]

[[File:Gray37.png|left|400 px]]

Hmm so basically we do the peer review the week after mid sem break until the 23rd of september, and we paste both the review on the groups page and on your own page... also apparently the other student discontinued the course so its just us doing the project now =S --[[User:Z3224500|Jenny Huang]] 03:02, 2 September 2010 (UTC)

Yay!! looks awesome!! Sorry i couldnt be there today, could you let me know what Mark says? thanks :) - Jill --[[User:Z3265772|z3265772]] 23:59, 1 September 2010 (UTC)

I've uploaded the first pic... I hope it's ok and if I did the layers wrongly please tell me so I can edit... also how do you do referencing that is not from pubmed journals?--[[User:Z3224500|Jenny]] 23:18, 1 September 2010 (UTC)

Hi Jenny, are you doing the drawn figure still? would you possibly be able to upload it before thursday? i have updated references for my section :) - Jill --[[User:Z3265772|z3265772]] 08:52, 1 September 2010 (UTC)

--[[User:S8600021|Mark Hill]] 00:49, 31 August 2010 (UTC) I have emailed your missing team member , but have not had a response yet. Your should continue to work on the project together as best you can. It seems to be progressing, though I did ask you to update your reference format and I do not see a student drawn figure. You need to have this updated before this weeks lab when I will be reviewing all projects.

Hi Jill, I'm working on it :) by the way have you heard from the other team member? Oh and I'll be drawing pictures for both the transcervical and transabdominal techniques..--[[User:Z3224500|Jenny Huang]] 07:46, 30 August 2010 (UTC)

Hi guys, only two weeks to go, we really need to do some more work, the editing at the end will be the hardest, so the sooner we finish, the easier it will be. - Jill--[[User:Z3265772|z3265772]] 23:46, 29 August 2010 (UTC)

Can we incorporate some sort of timeline? what do you think? maybe we can do a timeline of embryo development and note the time that CVS is done - Jill --[[User:Z3265772|z3265772]] 00:57, 26 August 2010 (UTC)

Mark has kindly shown us how to reference, ill try to sort that out tonight or tomorrow - Jill --[[User:Z3265772|z3265772]] 23:16, 25 August 2010 (UTC)

Ive just discovered, you can use almost any picture on wiki, the copyrights have usually expired, which is why wiki can use them, just search CVS on wiki and if there is a picture you like, check the copyright and copy away!! :D -Jill --[[User:Z3265772|z3265772]] 01:05, 25 August 2010 (UTC)

Hi guys, please feel free to edit any work i have done, or add to it, or even suggest to me on this page what to add. what i have put up so far really is a rough draft and will be trying to add to it later anyway :) -Jill --[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

{{Template:Projects10MHtalk}}

Hi guys, we need to get on top of this, its due for peer assessment in 3 weeks! Im going to do related research. does anyone want to do the drawing? ill also try and get some more references and photos up, as Mark has suggested. If you want a picture, just email the website with the picture on it, thats what ive been doing, they are usually pretty good about it. let me know of any other ideas you guys might have - Jill --[[User:Z3265772|z3265772]] 09:50, 23 August 2010 (UTC)

--[[User:S8600021|Mark Hill]] 04:35, 23 August 2010 (UTC) OK there are a few references here, but you will need more than these few and there should be some related images.

Link for group assessment criteria: [[2010_Lab_1#Group_Assessment_Criteria|group assessment criteria]] - Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

For current associated research:

http://onlinelibrary.wiley.com/doi/10.1002/pd.2410/abstract

http://www.ncbi.nlm.nih.gov/pubmed/11263542

http://www.ncbi.nlm.nih.gov/pubmed/19683693

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T7V-4BWVXPY-F9&_user=10&_coverDate=03%2F31%2F1994&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1427646674&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a3c3f2d47ad01c562a3baea8c60a48bc

http://www.informaworld.com/smpp/content~db=all~content=a913951525

http://www.escardiocontent.org/periodicals/ejcpr/article/S0002-9378%2807%2900305-5/abstract

http://humrep.oxfordjournals.org/cgi/content/abstract/3/6/811

- Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

Hi guys, i put up the link for Search Pubmed for our topic, did we want to assign ourselves a role to do or just see how the page goes? i thought maybe we could find a page that we like and follow a similar format, that way we know what our page will look like and can follow a layout as we go. -Jill --[[User:Z3265772|z3265772]] 01:12, 9 August 2010 (UTC)

also, see this web page http://www.cdc.gov/mmwr/preview/mmwrhtml/00038393.htm Jill --[[User:Z3265772|z3265772]] 11:16, 9 August 2010 (UTC)

project outline:

1. Intro

2. historic background

3. current associated research

4. simplified description of technique

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

5. student drawn figure or animation

6. reference list

7. glossary

8. external links

-Jill --[[User:Z3265772|z3265772]] 03:05, 11 August 2010 (UTC)

Can anyone tell me how to paste a picture from an outside source? i cant seem to figure it out. thanks :)
-Jill --[[User:Z3265772|z3265772]] 05:03, 11 August 2010 (UTC)

dont worry, i figured it out :)

i think we should put the references list on this page to begin with to make sure we dont double up
- Jill --[[User:Z3265772|z3265772]] 05:31, 11 August 2010 (UTC)

Hey guys sorry for the delay in replies. I see you have made a contribution to the topic already :) By the way, where did you find the project outline criteria? Oh and if you don't mind I can do research on the description of technique and current research. Feel free to contribute :) oh and any ideas on how to work on the drawings? --[[User:Z3224500|Jenny Huang]] 15:29, 11 August 2010 (UTC)

Hello guys,

So I found some journal articles that is of interest especially this one: http://apps.who.int/rhl/reviews/langs/CD003252.pdf which is long and has extensive information on the topic..
So I'll be editing my section in word and will be posting some info on technique in the future.

Btw here are some other articles that are of interest that can be accessed through unsw sirius:

http://linkinghub.elsevier.com/retrieve/pii/S0889854505702916

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

http://journals.lww.com/co-obgyn/Abstract/2005/04000/Chorionic_villus_sampling_and_amniocentesis.16.aspx

Complications:

http://journals.lww.com/greenjournal/Abstract/2007/09000/Procedure_Related_Complications_of_Amniocentesis.24.aspx

http://journals.lww.com/greenjournal/Abstract/2008/10000/Evaluating_the_Rate_and_Risk_Factors_for_Fetal.12.aspx

I'll be adding more once I find some that are useful..

Oh and about the topic headings are we just going to use the ones in the assesment criteria?

--[[User:Z3224500|z3224500]] 15:03, 24 August 2010 (UTC)

Hey Jenny!! i think its a great idea to use more headings, add as many as you like/can think of, i just cant think of any more. i think the assessment criteria is just the bare minimum we have to do, so please add more! Also, can we add the new discussion posts to the top of the page? so we dont have to scroll to the bottom every time? what do you think? (it says up the top of this page to add newer material at the top, just wondering what you thought). i really like the articles you have found too :) see you tomorrow
- Jill --[[User:Z3265772|z3265772]] 00:29, 25 August 2010 (UTC)

2010 Group Project 2

2010-10-06T12:06:50Z

Z3224500: /* Ethical concerns */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=
[[File:Gray37.png|right|thumb|280px|Sample is taken from the chorionic villi]]
[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. Between 10-12 weeks of pregnancy, the developing gestational sac is composed of a thick, outer chorionic membrane surrounding the amniotic cavity, a thin amniotic membrane and the chorionic cavity. The chorionic villi have now degenerated over most of the outer membrane, forming the chorion laeve, and the remaining villi fuses and embeds loosely into the decidua basalis. This forms the chorion frondosum, which will ultimately become the placenta. At this stage, the villi float freely in the blood of the intervillus space. Each villi is branched, and is composed of an outer syncytiotrophoblast and an inner cytotrophoblast layer. Within the centre of each villus is a mesenchymal core which contain capillaries carrying fetal blood. In CVS, usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.<ref>Jenkins, T.M, Wapner, R.J, 1999. First trimester prenatal diagnosis: Chorionic villus sampling. Seminars in Perinatology. pp403-413.</ref>

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. Women who had transcervical sampling had higher occurrence of fluid leakage and spotting. When a tenaculum is not used, the occurrence of vaginal spotting and bleeding continued. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory, which is a laboratory that analyses the number and shape of the chromosomes in cells. At the laboratory the cells are cultured (stimulated to grow and divide) for approximately 12 days. After enough cells are cultured, a banded karyotype is completed. This is where the fetal chromosomes in the cultured cells are stained and then photographed. The photographed chromosomes are then ordered, counted and checked for abnormalities.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors.<ref>Cica. N., 1998. Abortion Law in Australia. Parliament of Australia, Parliamentary Library. Accessed September 29. 2010. <http://www.aph.gov.au/library/pubs/rp/1998-99/99rp01.htm></ref> If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

'''Bioethics'''

The Bioethics involved in Health Care that encompasses medical practices including prenatal diagnosis methods aim to ensure that human values are respected in terms of healthcare institutions, life technology, health professions and clinical practices.<ref>Southern Cross Bioethics Institute. 2008. Bioethical Issues. Accessed 6 October, 2010. <http://www.bioethics.org.au/Resources/Bioethical%20Issues.html></ref>
Maintaining good practices in CVS testing and any other prenatal testing is essential to exercise the duty of care and to reduce any sort of harm upon the expectant mother. CVS:

*Should not be performed under 10 weeks gestation.
*Should be performed by an experienced, well trained technician
*Written consent should be obtained before testing
*Clinicians should use the CVS technique with which they are competent, using local anaesthesia for transabdominal CVS.
<ref>Royal Collage of Obstetricians and Gynaecologyists. 2010. Green-top Guideline No. 8 Amniocentesis and Chorionic Villus Sampling. Accessed 6 October, 2010. <http://www.rcog.org.uk/files/rcog-corp/GT8Amniocentesis0610.pdf></ref>

[[File:AbortionLawMap.png|thumb|right|200px|A World Map showing the legal status of abortion in different countries. Enlarge for legend.]]
'''Abortion'''

Abortion is a subject that brings about a wide number of ethical concerns whether morally, religiously and politically around the world.
Usually a community's beliefs and moral views are reflected in political decisions, although debate continues to be ongoing whether it is morally right to terminate a pregnancy before a normal childbirth, given a range of different circumstances people believe is acceptable. In Australia, abortion laws are present and differ by state, and is usually based on the mother's choice, given that she conforms to the restrictions of the law.

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling and Prenatal diagnosis techniques=

[[File:FISH_(technique).gif‎|thumb|250 px|FISH technique]]

[[File:Comparative_Genomics.jpg|thumb|250 px|Comparative Genomics]]

Prenatal diagnosis has been used to detect chromosomal abnormalities, especially Down’s syndrome, for over 30 years. As we have discussed on this page, the most common forms of prenatal diagnosis are amniocentesis, CVS and ultrasound. The type of test used depends on the history of the parents, any abnormalities detected in the initial ultrasound examination, and preferences of the parents. Testing for chromosomal abnormalities using amniocentesis and CVS is invasive and somewhat time consuming. Some recent advancements in this field include the use of fluorescence in situ hybridisation (FISH), quantitative fluorescence-PCR techniques, and comparative genomics. Although these techniques are currently still invasive, the waiting time for these tests is usually only 1 to 2 days for chromosomal abnormalities. <ref><pubmed>20014413</pubmed></ref> This waiting time would mean a much less stressful waiting period for the parents. The future of prenatal diagnosis certainly lies in the field of non invasive techniques, and research in the field of prenatal diagnosis is looking toward making detection of abnormalities non invasive, using the fetal cells from maternal circulation. <ref><pubmed>20014413</pubmed></ref>

'''Fluorescence in situ hybridisation (FISH):''' FISH is a cytogenetic technique, involving analysing the number and shape of the chromosomes of cells. FISH detects the addition or deletion of specific DNA sequences on chromosomes using florescent probes that bind to a similar sequence of chromosomes. Once the florescence probes are attached, fluorescence microscopy is used to view the chromosomes and detect the abnormality. In prenatal diagnosis, FISH is useful for detecting trisomy and monosomy conditions.[http://en.wikipedia.org/wiki/Fluorescent_in_situ_hybridization More about FISH]

'''Comparative genomics:''' Comparative Genomics is a very new research field where the genome sequence of different organisms are compared. This comparison between organisms shows where a species genomes have been conserved (stabilising selection) and where differences occur (positive selection). Many species share the same genes, and comparative genomics can show what species share genes and which genes are different among species. This information can help us understand the function of different genes and identify and control diseases. The purpose is to gain a better understanding of how species have evolved and to determine the function of genes. In prenatal diagnosis, fetal cells can be viewed and compared against both parents genome, any change that deviates from the normal pattern due to too much or too little DNA can be seen, this deviation of the normal pattern means a certain chromosome has either been copied or deleted, causing disease. [http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml More about Comparative Genomics]

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

File:AbortionLawMap.png

2010-10-06T12:04:46Z

Z3224500:

World map demonstrating the legal status of abortion laws globally.

=Legend:=

'''Blue:''' Legal on demand

'''Yellow:''' legal to preserve maternal life, health, rape, foetal defects and socio-economic factors.

'''Brown:''' Legal with exception for maternal life, health, rape and defects.

'''Orange:''' Illegal with exception for maternal life, health and rape

'''Pink:''' Illegal with exception for maternal life, health

'''Dark blue:''' Illegal

'''Black:''' Varies by State

'''Grey:''' N/A

'''Copyright Information:'''

Sourced from:http://en.wikipedia.org/wiki/File:AbortionLawsMap-NoLegend.png

"I, the copyright holder of this work, hereby release it into the public domain. This applies worldwide.

In case this is not legally possible:
I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law."

2010 Group Project 2

2010-10-06T12:02:13Z

Z3224500: /* Ethical concerns */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=
[[File:Gray37.png|right|thumb|280px|Sample is taken from the chorionic villi]]
[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. Between 10-12 weeks of pregnancy, the developing gestational sac is composed of a thick, outer chorionic membrane surrounding the amniotic cavity, a thin amniotic membrane and the chorionic cavity. The chorionic villi have now degenerated over most of the outer membrane, forming the chorion laeve, and the remaining villi fuses and embeds loosely into the decidua basalis. This forms the chorion frondosum, which will ultimately become the placenta. At this stage, the villi float freely in the blood of the intervillus space. Each villi is branched, and is composed of an outer syncytiotrophoblast and an inner cytotrophoblast layer. Within the centre of each villus is a mesenchymal core which contain capillaries carrying fetal blood. In CVS, usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.<ref>Jenkins, T.M, Wapner, R.J, 1999. First trimester prenatal diagnosis: Chorionic villus sampling. Seminars in Perinatology. pp403-413.</ref>

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. Women who had transcervical sampling had higher occurrence of fluid leakage and spotting. When a tenaculum is not used, the occurrence of vaginal spotting and bleeding continued. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory, which is a laboratory that analyses the number and shape of the chromosomes in cells. At the laboratory the cells are cultured (stimulated to grow and divide) for approximately 12 days. After enough cells are cultured, a banded karyotype is completed. This is where the fetal chromosomes in the cultured cells are stained and then photographed. The photographed chromosomes are then ordered, counted and checked for abnormalities.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors.<ref>Cica. N., 1998. Abortion Law in Australia. Parliament of Australia, Parliamentary Library. Accessed September 29. 2010. <http://www.aph.gov.au/library/pubs/rp/1998-99/99rp01.htm></ref> If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

'''Bioethics'''

The Bioethics involved in Health Care that encompasses medical practices including prenatal diagnosis methods aim to ensure that human values are respected in terms of healthcare institutions, life technology, health professions and clinical practices.<ref>Southern Cross Bioethics Institute. 2008. Bioethical Issues. Accessed 6 October, 2010. <http://www.bioethics.org.au/Resources/Bioethical%20Issues.html></ref>
Maintaining good practices in CVS testing and any other prenatal testing is essential to exercise the duty of care and to reduce any sort of harm upon the expectant mother. CVS:

*Should not be performed under 10 weeks gestation.
*Should be performed by an experienced, well trained technician
*Written consent should be obtained before testing
*Clinicians should use the CVS technique with which they are competent, using local anaesthesia for transabdominal CVS.
<ref>Royal Collage of Obstetricians and Gynaecologyists. 2010. Green-top Guideline No. 8 Amniocentesis and Chorionic Villus Sampling. Accessed 6 October, 2010. <http://www.rcog.org.uk/files/rcog-corp/GT8Amniocentesis0610.pdf></ref>

'''Abortion'''
[[File:AbortionLawMap.png|thumb|right|200px|A World Map showing the legal status of abortion in different countries. Enlarge for legend.]]
Abortion is a subject that brings about a wide number of ethical concerns whether morally, religiously and politically around the world.
Usually a community's beliefs and moral views are reflected in political decisions, although debate continues to be ongoing whether it is morally right to terminate a pregnancy before a normal childbirth, given a range of different circumstances people believe is acceptable. In Australia, abortion laws are present and differ by state, and is usually based on the mother's choice, given that she conforms to the restrictions of the law.

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling and Prenatal diagnosis techniques=

[[File:FISH_(technique).gif‎|thumb|250 px|FISH technique]]

[[File:Comparative_Genomics.jpg|thumb|250 px|Comparative Genomics]]

Prenatal diagnosis has been used to detect chromosomal abnormalities, especially Down’s syndrome, for over 30 years. As we have discussed on this page, the most common forms of prenatal diagnosis are amniocentesis, CVS and ultrasound. The type of test used depends on the history of the parents, any abnormalities detected in the initial ultrasound examination, and preferences of the parents. Testing for chromosomal abnormalities using amniocentesis and CVS is invasive and somewhat time consuming. Some recent advancements in this field include the use of fluorescence in situ hybridisation (FISH), quantitative fluorescence-PCR techniques, and comparative genomics. Although these techniques are currently still invasive, the waiting time for these tests is usually only 1 to 2 days for chromosomal abnormalities. <ref><pubmed>20014413</pubmed></ref> This waiting time would mean a much less stressful waiting period for the parents. The future of prenatal diagnosis certainly lies in the field of non invasive techniques, and research in the field of prenatal diagnosis is looking toward making detection of abnormalities non invasive, using the fetal cells from maternal circulation. <ref><pubmed>20014413</pubmed></ref>

'''Fluorescence in situ hybridisation (FISH):''' FISH is a cytogenetic technique, involving analysing the number and shape of the chromosomes of cells. FISH detects the addition or deletion of specific DNA sequences on chromosomes using florescent probes that bind to a similar sequence of chromosomes. Once the florescence probes are attached, fluorescence microscopy is used to view the chromosomes and detect the abnormality. In prenatal diagnosis, FISH is useful for detecting trisomy and monosomy conditions.[http://en.wikipedia.org/wiki/Fluorescent_in_situ_hybridization More about FISH]

'''Comparative genomics:''' Comparative Genomics is a very new research field where the genome sequence of different organisms are compared. This comparison between organisms shows where a species genomes have been conserved (stabilising selection) and where differences occur (positive selection). Many species share the same genes, and comparative genomics can show what species share genes and which genes are different among species. This information can help us understand the function of different genes and identify and control diseases. The purpose is to gain a better understanding of how species have evolved and to determine the function of genes. In prenatal diagnosis, fetal cells can be viewed and compared against both parents genome, any change that deviates from the normal pattern due to too much or too little DNA can be seen, this deviation of the normal pattern means a certain chromosome has either been copied or deleted, causing disease. [http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml More about Comparative Genomics]

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

File:AbortionLawMap.png

2010-10-06T11:57:55Z

Z3224500: World Map demonstrating the legal status of abortion laws globally. Legend: Blue: Legal on demand Yellow: legal to preserve maternal life, health, rape, foetal defects and socio-economic factors. Brown: Legal with exception for maternal life, health, ra

World Map demonstrating the legal status of abortion laws globally.

Legend:
Blue: Legal on demand
Yellow: legal to preserve maternal life, health, rape, foetal defects and socio-economic factors.
Brown: Legal with exception for maternal life, health, rape and defects.
Orange: Illegal with exception for maternal life, health and rape
Pink: Illegal with exception for maternal life, health
Dark blue: Illegal
Black: Varies by State
Grey: N/A

Copyright Information:
Sourced from:http://en.wikipedia.org/wiki/File:AbortionLawsMap-NoLegend.png

"I, the copyright holder of this work, hereby release it into the public domain. This applies worldwide.

In case this is not legally possible:
I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law."

2010 Group Project 2

2010-10-06T11:41:04Z

Z3224500: /* Ethical concerns */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=
[[File:Gray37.png|right|thumb|280px|Sample is taken from the chorionic villi]]
[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. Between 10-12 weeks of pregnancy, the developing gestational sac is composed of a thick, outer chorionic membrane surrounding the amniotic cavity, a thin amniotic membrane and the chorionic cavity. The chorionic villi have now degenerated over most of the outer membrane, forming the chorion laeve, and the remaining villi fuses and embeds loosely into the decidua basalis. This forms the chorion frondosum, which will ultimately become the placenta. At this stage, the villi float freely in the blood of the intervillus space. Each villi is branched, and is composed of an outer syncytiotrophoblast and an inner cytotrophoblast layer. Within the centre of each villus is a mesenchymal core which contain capillaries carrying fetal blood. In CVS, usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.<ref>Jenkins, T.M, Wapner, R.J, 1999. First trimester prenatal diagnosis: Chorionic villus sampling. Seminars in Perinatology. pp403-413.</ref>

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. Women who had transcervical sampling had higher occurrence of fluid leakage and spotting. When a tenaculum is not used, the occurrence of vaginal spotting and bleeding continued. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory, which is a laboratory that analyses the number and shape of the chromosomes in cells. At the laboratory the cells are cultured (stimulated to grow and divide) for approximately 12 days. After enough cells are cultured, a banded karyotype is completed. This is where the fetal chromosomes in the cultured cells are stained and then photographed. The photographed chromosomes are then ordered, counted and checked for abnormalities.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors.<ref>Cica. N., 1998. Abortion Law in Australia. Parliament of Australia, Parliamentary Library. Accessed September 29. 2010. <http://www.aph.gov.au/library/pubs/rp/1998-99/99rp01.htm></ref> If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

'''Bioethics'''

The Bioethics involved in Health Care that encompasses medical practices including prenatal diagnosis methods aim to ensure that human values are respected in terms of healthcare institutions, life technology, health professions and clinical practices.<ref>Southern Cross Bioethics Institute. 2008. Bioethical Issues. Accessed 6 October, 2010. <http://www.bioethics.org.au/Resources/Bioethical%20Issues.html></ref>
Maintaining good practices in CVS testing and any other prenatal testing is essential to exercise the duty of care and to reduce any sort of harm upon the expectant mother. CVS:

*Should not be performed under 10 weeks gestation.
*Should be performed by an experienced, well trained technician
*Written consent should be obtained before testing
*Clinicians should use the CVS technique with which they are competent, using local anaesthesia for transabdominal CVS.
<ref>Royal Collage of Obstetricians and Gynaecologyists. 2010. Green-top Guideline No. 8 Amniocentesis and Chorionic Villus Sampling. Accessed 6 October, 2010. <http://www.rcog.org.uk/files/rcog-corp/GT8Amniocentesis0610.pdf></ref>

'''Abortion'''

Abortion is a subject that brings about a wide number of ethical concerns whether morally, religiously and politically around the world.
Usually a community's beliefs and moral views are reflected in political decisions, although debate continues to be ongoing whether it is morally right to terminate a pregnancy before a normal childbirth, given a range of different circumstances people believe is acceptable. In Australia, abortion laws are present and differ by state, and is usually based on the mother's choice, given that she conforms to the restrictions of the law.

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling and Prenatal diagnosis techniques=

[[File:FISH_(technique).gif‎|thumb|250 px|FISH technique]]

[[File:Comparative_Genomics.jpg|thumb|250 px|Comparative Genomics]]

Prenatal diagnosis has been used to detect chromosomal abnormalities, especially Down’s syndrome, for over 30 years. As we have discussed on this page, the most common forms of prenatal diagnosis are amniocentesis, CVS and ultrasound. The type of test used depends on the history of the parents, any abnormalities detected in the initial ultrasound examination, and preferences of the parents. Testing for chromosomal abnormalities using amniocentesis and CVS is invasive and somewhat time consuming. Some recent advancements in this field include the use of fluorescence in situ hybridisation (FISH), quantitative fluorescence-PCR techniques, and comparative genomics. Although these techniques are currently still invasive, the waiting time for these tests is usually only 1 to 2 days for chromosomal abnormalities. <ref><pubmed>20014413</pubmed></ref> This waiting time would mean a much less stressful waiting period for the parents. The future of prenatal diagnosis certainly lies in the field of non invasive techniques, and research in the field of prenatal diagnosis is looking toward making detection of abnormalities non invasive, using the fetal cells from maternal circulation. <ref><pubmed>20014413</pubmed></ref>

'''Fluorescence in situ hybridisation (FISH):''' FISH is a cytogenetic technique, involving analysing the number and shape of the chromosomes of cells. FISH detects the addition or deletion of specific DNA sequences on chromosomes using florescent probes that bind to a similar sequence of chromosomes. Once the florescence probes are attached, fluorescence microscopy is used to view the chromosomes and detect the abnormality. In prenatal diagnosis, FISH is useful for detecting trisomy and monosomy conditions.[http://en.wikipedia.org/wiki/Fluorescent_in_situ_hybridization More about FISH]

'''Comparative genomics:''' Comparative Genomics is a very new research field where the genome sequence of different organisms are compared. This comparison between organisms shows where a species genomes have been conserved (stabilising selection) and where differences occur (positive selection). Many species share the same genes, and comparative genomics can show what species share genes and which genes are different among species. This information can help us understand the function of different genes and identify and control diseases. The purpose is to gain a better understanding of how species have evolved and to determine the function of genes. In prenatal diagnosis, fetal cells can be viewed and compared against both parents genome, any change that deviates from the normal pattern due to too much or too little DNA can be seen, this deviation of the normal pattern means a certain chromosome has either been copied or deleted, causing disease. [http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml More about Comparative Genomics]

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

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[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-10-06T11:31:06Z

Z3224500: /* Ethical concerns */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=
[[File:Gray37.png|right|thumb|280px|Sample is taken from the chorionic villi]]
[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. Between 10-12 weeks of pregnancy, the developing gestational sac is composed of a thick, outer chorionic membrane surrounding the amniotic cavity, a thin amniotic membrane and the chorionic cavity. The chorionic villi have now degenerated over most of the outer membrane, forming the chorion laeve, and the remaining villi fuses and embeds loosely into the decidua basalis. This forms the chorion frondosum, which will ultimately become the placenta. At this stage, the villi float freely in the blood of the intervillus space. Each villi is branched, and is composed of an outer syncytiotrophoblast and an inner cytotrophoblast layer. Within the centre of each villus is a mesenchymal core which contain capillaries carrying fetal blood. In CVS, usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.<ref>Jenkins, T.M, Wapner, R.J, 1999. First trimester prenatal diagnosis: Chorionic villus sampling. Seminars in Perinatology. pp403-413.</ref>

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. Women who had transcervical sampling had higher occurrence of fluid leakage and spotting. When a tenaculum is not used, the occurrence of vaginal spotting and bleeding continued. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory, which is a laboratory that analyses the number and shape of the chromosomes in cells. At the laboratory the cells are cultured (stimulated to grow and divide) for approximately 12 days. After enough cells are cultured, a banded karyotype is completed. This is where the fetal chromosomes in the cultured cells are stained and then photographed. The photographed chromosomes are then ordered, counted and checked for abnormalities.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors.<ref>Cica. N., 1998. Abortion Law in Australia. Parliament of Australia, Parliamentary Library. Accessed September 29. 2010. <http://www.aph.gov.au/library/pubs/rp/1998-99/99rp01.htm></ref> If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

'''Bioethics'''

The Bioethics involved in Health Care that encompasses medical practices including prenatal diagnosis methods aim to ensure that human values are respected in terms of healthcare institutions, life technology, health professions and clinical practices.
Maintaining good practices in CVS testing and any other prenatal testing is essential to exercise the duty of care and to reduce any sort of harm upon the expectant mother. CVS:

*Should not be performed under 10 weeks gestation.
*Should be performed by an experienced, well trained technician
*Written consent should be obtained before testing
*Clinicians should use the CVS technique with which they are competent, using local anaesthesia for transabdominal CVS.

'''Abortion'''

Abortion is a subject that brings about a wide number of ethical concerns whether morally, religiously and politically around the world.
Usually a community's beliefs and moral views are reflected in political decisions, although debate continues to be ongoing whether it is morally right to terminate a pregnancy before a normal childbirth, given a range of different circumstances people believe is acceptable. In Australia, abortion laws are present and differ by state, and is usually based on the mother's choice, given that she conforms to the restrictions of the law.

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling and Prenatal diagnosis techniques=

[[File:FISH_(technique).gif‎|thumb|250 px|FISH technique]]

[[File:Comparative_Genomics.jpg|thumb|250 px|Comparative Genomics]]

Prenatal diagnosis has been used to detect chromosomal abnormalities, especially Down’s syndrome, for over 30 years. As we have discussed on this page, the most common forms of prenatal diagnosis are amniocentesis, CVS and ultrasound. The type of test used depends on the history of the parents, any abnormalities detected in the initial ultrasound examination, and preferences of the parents. Testing for chromosomal abnormalities using amniocentesis and CVS is invasive and somewhat time consuming. Some recent advancements in this field include the use of fluorescence in situ hybridisation (FISH), quantitative fluorescence-PCR techniques, and comparative genomics. Although these techniques are currently still invasive, the waiting time for these tests is usually only 1 to 2 days for chromosomal abnormalities. <ref><pubmed>20014413</pubmed></ref> This waiting time would mean a much less stressful waiting period for the parents. The future of prenatal diagnosis certainly lies in the field of non invasive techniques, and research in the field of prenatal diagnosis is looking toward making detection of abnormalities non invasive, using the fetal cells from maternal circulation. <ref><pubmed>20014413</pubmed></ref>

'''Fluorescence in situ hybridisation (FISH):''' FISH is a cytogenetic technique, involving analysing the number and shape of the chromosomes of cells. FISH detects the addition or deletion of specific DNA sequences on chromosomes using florescent probes that bind to a similar sequence of chromosomes. Once the florescence probes are attached, fluorescence microscopy is used to view the chromosomes and detect the abnormality. In prenatal diagnosis, FISH is useful for detecting trisomy and monosomy conditions.[http://en.wikipedia.org/wiki/Fluorescent_in_situ_hybridization More about FISH]

'''Comparative genomics:''' Comparative Genomics is a very new research field where the genome sequence of different organisms are compared. This comparison between organisms shows where a species genomes have been conserved (stabilising selection) and where differences occur (positive selection). Many species share the same genes, and comparative genomics can show what species share genes and which genes are different among species. This information can help us understand the function of different genes and identify and control diseases. The purpose is to gain a better understanding of how species have evolved and to determine the function of genes. In prenatal diagnosis, fetal cells can be viewed and compared against both parents genome, any change that deviates from the normal pattern due to too much or too little DNA can be seen, this deviation of the normal pattern means a certain chromosome has either been copied or deleted, causing disease. [http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml More about Comparative Genomics]

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

Talk:2010 Group Project 2

2010-10-06T06:33:10Z

Z3224500:

yes our page looks very good :D ohhh sorry for the delay on the ethics part.. I had 2 assignments that were due just the other day... no worries I'll be done by tonight :D--[[User:Z3224500|Jenny Huang]] 06:33, 6 October 2010 (UTC)

LOVE our page!!! looks awesome! i think we have done everything we can to get maximum marks, and i have learnt heaps doing it! Dont forget Mark is locking the page at some stage as its due tomorrow (i think he will prob lock them tomorrow morning or something). If you need help with any of your sections let me know, i have finished my bits :D yay!! --[[User:Z3265772|z3265772]] 04:50, 6 October 2010 (UTC)

Umm.. I'm not sure about that, because the sources I found mosaicism on had it in their "limitations" heading... --[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)--[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)

Hey Jenny, do you think Mosaicism should be in the abnormalities found by CVS section? a few people have commented that its a bit confusing what the test detects and the risks associated with testing. i think Mosaicism is more under the heading of what cvs detects --[[User:Z3265772|z3265772]] 04:16, 23 September 2010 (UTC)

hey jill,
group 6 here, you may use our picture

--[[User:Z3254433|z3254433]] 09:07, 26 September 2010 (UTC)

===to fix===

'''Begin''' by collating the comments.
* What are the common criticisms?
* What were the best aspects identified within your project?
* What errors, typos, missing references were identified?
* Were there contributions from individual group members that were identified as good or poor parts of the overall project?

'''Then''' work on the changes.
* Develop priorities.
* Divide the changes and corrections between group members.
* Are there additional changes that should be made that were not identified by peer assessment.

'''Jill:'''

DONE abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? comparative genomics, Improvements?

DONE future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether

DONE move glossary above references so you dont have to scroll all the way down to read them

DONE table comparing other techniques

DONE got confused between the risks of this test and what it predicted (this will be clear in the above table)

DONE -it didn't state that the test was invasive in intro (table)

DONE -All spelling amd grammar - some more editing of spelling is required

DONE "abnormalities found by CVS" section towards the top of the page coz I got confused between the risks of this test and what it predicted

DONE -link or a reference to the brief time line where you state the names of the authors

DONE -The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed

DONE -I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources

DONE -a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work

DONE - it would be that you put the advantages/disadvantages of CVS over other techniques in a table.

'''Jenny:'''

flowchart or more pictures of procedure

DONE clarify what hypertension is in the hypertensive disorders of pregnancy section

outcomes + ethics,

DONE Are the transabdominal and the transcervical pictures the student-drawn ones? put up in discussion that you drew them and you give permission for re-use - Jenny, ive done this for you, all you need to do is edit and add your student number, -Jill

DONE elaborate on procedure eg what cells are being taken etc and stages of chorionic villus in embryology

DONE Spelling and grammar, - Jenny, ive gone through the page and edited the spelling mistakes i could find, could you please do the same incase ive missed any? and double check the sections you are about to write? Thanks :) - Jill --[[User:Z3265772|z3265772]] 00:33, 24 September 2010 (UTC)

The current research section could be put more into point form to make it more inviting to read - not sure if you want to do this, i think its ok as it is, maybe just delete this suggestion? or add pictures of people researching? haha

----

==Peer Review==

'''Please note!''' when posting your peer review, we only have two group members. the other one dropped out. Thanks :)

--[[User:Z3129413]] 16:29, 22 September 2010 (UTC)
I love those old timey pencil medical pictures and so for me this was really great, what instantly nailed the whole positive immediate impression was 'Reasons for getting chorionic villus sampling etc etc' right there at the beginning. Why would I get one? thanks very much. Perhaps a darker font would make it even better. Historical back ground is really good and technique pictures are of high standard. The table presentation of abnormalities found and ratios is such an effective way of portraying this information.

A few Q's with the hypertension cvs topic,
Is there a normally expected percent of women in a large population to develop hypertensive disorders, just for perspective? CVS would not lower incidences of such surely (9098 pop, 2.7% to 7.1% control). 138 study size seems a bit low, is result really much more significant? However I did understand that CVS was more risk prone than amniocentesis for pre eclampsia and gestational hypertension.
This project is well on track.

Group 2: Your project is very impressive in content as well as organisation. The most notable thing for me was the wide use of pictures which must have taken a lot of time and effort to source. They definitely create an engaging page especially in conjunction with the use of tables and clear subheadings. The structure you have used is very effective as it allows your information to be scientific and thorough but at the same time it is concise and easy to navigate. I felt like i got an extensive overview of CVS after having read your page and the use of pictures and subheadings kept it from being a chore. I felt the history and abnormalities sections were particularly interesting. I also appreciate how you have seemed to approach this topic from all angles and not just a one-sided, all current and positive viewpoint. To improve your page perhaps you could explore the future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether. Either way your page is probably up to standard as it is and it is obvious that you have worked hard at it. Job well done.
--[[User:Z3293029|z3293029]] 14:38, 22 September 2010 (UTC)

Group 2: fantastic use of images, it definitely worked to your advantage in engaging your audience's attention. Over all the language used is relatively easy to follow yet informative. As someone has already mentioned, some more editing of spelling is required. The amount of attention to detail is evident in the references which are from a range of sources so well done. I particularly liked that the page covered accuracy and limitations of the diagnostic procedure. Something that lacked clarity in a few other groups. Good use of the table covering the abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? Improvements?
Just an idea. Well done overall. --z3241780 13:40, 22 September 2010 (UTC)

'''GROUP 2: Chorionic Villi Sampling'''

This page caught my attention as soon as I saw it and that made me want to read on and thus learn about Chorionic Villi Sampling. A lot of research has gone into this assignment and it’s evident in the information presented as its precise which also helps capture the readers. The amount of research is also evident in the long list of references. The webpage is actually extremely informative covering pretty much every aspect of the pre-natal diagnostic techniques. Your webpage has the most pictures and this helps it stand out as one of the best project pages. I really, really like the formatting and the tables. The images break up the information so you’re never overloaded with the amount of text. The only bit of criticism is spelling but this is extremely minor as you’ll pick up on the spelling mistakes when you go over the page. The language in is the right mixture of scientific language meaning that even people without a scientific background can understand the CVS. Great job guys you really can’t tell that only two people are in this group. It’s extremely good!!! I also really like the first picture you have, gives a page a really good feel to it.

--[[User:Z3252635|z3252635]] 13:20, 22 September 2010 (UTC)

Hi guys!

You have found so many great pictures! Your page looks amazing. I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources. Your timeline was great too; I really like how you put up the concise timeline and then expanded a bit on the major developments afterwards. Are the transabdominal and the transcervical pictures the student-drawn ones? If so, well done! They’re really clear and beautifully done, but you should probably label them as student drawn and put in the copyright statement. If I could suggest something, it would be that you put the advantages/disadvantages of CVS over other techniques in a table. Otherwise, your page is really easy to read, and again has brilliant visuals – great job!--[[User:Z3252833|z3252833]] 12:42, 22 September 2010 (UTC)

CVS.

Group 2, your project is looking great, the first thing i noticed when reading it is that there is lots of detail which shows a great depth of research has gone into it, which is supported by your reference list. Another thing is the amount of pictures which support the information and break it up to make it easier to take in so much information at once. The disorders table provides great detail and makes it interesting with the pictures.

What could be improved: You could put the advantages/disadvantages into a table form to make it even easier to understand. The reasons to use this technique could be slotted into the procedure section instead of the introduction maybe as it shows who is eligible for the procedure. The current research section could be put more into point form to make it more inviting to read. But overall really great project.

--[[User:Z3292208|z3292208]] 08:55, 22 September 2010 (UTC)

This project is extremely well done. It seems a great effort has gone into proper referencing which also gives the impression of a thoughtful attempt. The balance of information mediums is great and the logical flow of ideas when reading through each section is perfect.
Suggestion: possibly more pictures or a flowchart of the procedure itself?

Well done :)

--[[User:Z3254753|z3254753]] 16:55, 21 September 2010 (UTC)

Group 2- This project had tons of photos which is super great because its much easier to follow... Most of the point made is supported with pictures ..definetly provided me a better understanding of CVS ..I agree with what others have mentioned its very informative and especially with just 2 team members .. fantastic work

what could be improved = a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work ..--[[User:Z3305561|Navneet Ahuja]] 12:53, 21 September 2010 (UTC)

Group project 2: chorionic villus sampling

This group had great images and the page layout was good too especially the tables which simplified the information and made it easier to read. The information presented was very informative, scientific, and all the key concepts were covered on the topic. The project had a very impressive reference list, and it did help in my understanding of this prenatal diagnostic technique.

What could be improved?
I did find a spelling mistake under the heading Results and Accuracy were you have written “maybe” instead of “baby”, so maybe proof read the assignment to pick up on any other possible spelling or grammatical errors, other than that well done.

--[[User:Z3254433|z3254433]] 07:15, 20 September 2010 (UTC)

This project was highly informative about CVS. It contained a lot of information in which it shows that a lot of research has gone into it. Everything has been covered like, what the test predicts and what risks are associated with this test. It was very scientific, yet easy to understand at a non-scientific level. I liked the external links how it directed me straight to a page of different articles about CVS.

What could be improved is maybe placing the "abnormalities found by CVS" section towards the top of the page, because i was a bit unsure on what this test predicted in the first place. I got confused between the risks of this test and what it predicted. But I managed to understand it all once all read through. Also, a definition of a "cannula" may be helpful in the glossary too, i wasn't sure what that exactly was.

--[[User:Z3291079|z3291079]] 02:48, 21 September 2010 (UTC)

This project provides a clear understanding of the key information regarding CVS, such as how it is carried out, the risks and benfits of CVS, what it is used for as well as future research. I have find the pictures to be of a great help in explaining the procedure of CVS.

One think I did notice was that, it didn't state that the test was invasive until you figure it out when you look at the pictures in the procedures. I think stating that in the introduction would make it clearer for readers to follow on with the information this projects provides having that knowledge in mind at the start.

--[[User:Z3216889|3216889]] 12:13, 22 September 2010 (UTC)

This web page is definitely one of my favorites. The information that you have provided is exceptional; the reference list is indicative of your extensive research. The table of deformities was a stand out for me as it was very well set out and was a effective break from the text. You also used excellent external links that were very well placed within the web page. A slight improvement would be to include a link or a reference to the brief time line where you state the names of the authors, and as previously mentioned, reference the statistics that you have included. Other than that, I applaud you for a job well done!--[[User:Z3252083|z3252083]] 12:22, 22 September 2010 (UTC)

--Group 2 Chronic villus sampling
This webpage shows that the group was very thorough in the research due to the amount of detail that has gone into it and its many links. The layout is very well set out which helps someone understand it if he/she has no previous knowledge of the concept. The use of pictures and diagrams were done well as it broke the page up making it very easy to read and take in the information. The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed. That’s all guys and well done considering you only had 2 people working on it.

--[[User:Z3290040|3290040]] 10:19, 22 September 2010 (UTC)

----

----

===group discussion===

I agree the page feels more "in order" now. yeh... its tough trying to find more information. I guess i'll expand on maybe on some of the abnormalities? I was thinking we can get pictures of the several diseases but it will probably be a little difficult due to copyright? hmm if i get new ideas from now until tommorrow i'll definately add more stuff in --[[User:Z3224500|Jenny Huang]] 06:38, 15 September 2010 (UTC)

Hey Jenny, i changed the order of the page around, i think it makes more sense now, before it didnt really flow from one section to the next, i think its a bit better, i tried to do it on this order, Intro, history, procedure, results, risks, advantages. that order seems to be how most wiki pages are set up, and how mark sets up his pages. what do you think? -Jill --[[User:Z3265772|z3265772]] 02:14, 15 September 2010 (UTC)

i think i searched prenatal diagnosis in the search box on the left, and mark has made a prenatal diagnosis page. the prenatal diagnosis terms were on that. ive been looking at last years pages, and they have so much content, but there just isnt that much information on CVS. theres only so much you can write about it. i guess we need to start thinking outside the box and adding general prenatal stuff on here too. thats why i thought maybe another table with a timeline of other techniques on it. ? ill just do it and see how it looks... -Jill --[[User:Z3265772|z3265772]] 01:47, 15 September 2010 (UTC)

hmm good idea.. btw what article did you find the terms for the prenatal diagnosis? should i incorporate that in the results section? --[[User:Z3224500|Jenny Huang]] 15:19, 14 September 2010 (UTC)

maybe we could also do ethical issues? -Jill --[[User:Z3265772|z3265772]] 12:35, 14 September 2010 (UTC)

Just an idea if we wanted to add more to the page, we could do another table, with the different diagnostic techniques used - eg ultrasound, AFP, amniocentesis and CVS etc and do a timeline with when each technique can be used, what it can test for, and how invasive it is. i know its not directly CVS, but it will give a good overview of the advantages and disadvantages etc. and im running out of ideas of what else we can have on here. can you think of anything else? -Jill --[[User:Z3265772|z3265772]] 12:30, 14 September 2010 (UTC)

Found out its due thurs, Sorry!! im doing malformations now, but we definitely need to add more content, last years pages had over 600 revisions, we only have 200. So add whatever you think we could do to improve the page. Thanks for your help over the weekend, i did feel alone in creating the page! Looks great now though! Maybe we could look at last years pages and see what we like about them, and maybe get some ideas on how to add to our page. im trying to put alot of effort in as its worth 20% of our final mark :) ive also added to the malformations part, ill keep doing that. Thanks!! -Jill --[[User:Z3265772|z3265772]] 02:24, 13 September 2010 (UTC)

Hey can't make it to lecture today.. but if its due for peer assesment today/this week, what suggestions do you think we can improve on? hmm also whos doing the part on malformations? --[[User:Z3224500|Jenny Huang]] 23:07, 12 September 2010 (UTC)

yeah good question.. ill see if i can find something more recent and let you know. i guess it would be. also, hope you dont mind, i put some of your references in, and added some pictures :) -Jill --[[User:Z3265772|z3265772]] 13:00, 12 September 2010 (UTC)

Hey for the section on malformations in current research, would it be limb defects? the articles I found were mostly from the 1990s so I'm not sure if I should use..--[[User:Z3224500|Jenny Huang]] 12:49, 12 September 2010 (UTC)

Yay it looks neat!!!glad you figured out how to fix the formatting.. It was rather confusing before haha. SOrry if it seems like you are doing most of the work :( I'll add to the current research to lighten off your load.i'll be working on it most of the weekend--[[User:Z3224500|Jenny Huang]] 16:39, 10 September 2010 (UTC)

I made a table!! it took AGES but it looks good :) we probably need to spread everything out a bit, it looks a bit crowded, but getting there! i separated the risks from current research :)- Jill --[[User:Z3265772|z3265772]] 12:03, 10 September 2010 (UTC)

Hmm it didn't take that long.. btw I've already done it but I haven't uploaded it yet but I'll do so now... hmm by the way should the heading "risks" be separate from the "current assosciated research" heading?--[[User:Z3224500|Jenny Huang]] 02:53, 10 September 2010 (UTC)

Hey! Did it take long to do the drawing for the transabdominal technique? i was thinking we could do a second one the same for transcervical. what do you think? - Jill --[[User:Z3265772|z3265772]] 02:09, 10 September 2010 (UTC)

Im pretty sure its due monday for peer assessment, thats what it says in the course guide. did he say it was due thurs in the lab last week? hope its due thurs! that would be awesome! - Jill --[[User:Z3265772|z3265772]] 12:00, 9 September 2010 (UTC)

Hey Jill, wow only 4 days! I was mistaken that it was due next thursday. But don't wrry, I'll have the whole weekend to finish up ;)--[[User:Z3224500|Jenny Huang]] 08:30, 9 September 2010 (UTC)

Hi! Ive used a reference that is not from pub med, so you can copy that to use references that arent in pub med. :) only 4 days till its due! - Jill --[[User:Z3265772|z3265772]] 01:29, 9 September 2010 (UTC)

some pictures we can use, this first one is Primary chorionic villi, the second picture is secondary chorionic villi, these may be helpful when describing the technique -Jill --[[User:Z3265772|z3265772]] 09:52, 7 September 2010 (UTC)

[[File:Gray36.png|left|400 px]]

[[File:Gray37.png|left|400 px]]

Hmm so basically we do the peer review the week after mid sem break until the 23rd of september, and we paste both the review on the groups page and on your own page... also apparently the other student discontinued the course so its just us doing the project now =S --[[User:Z3224500|Jenny Huang]] 03:02, 2 September 2010 (UTC)

Yay!! looks awesome!! Sorry i couldnt be there today, could you let me know what Mark says? thanks :) - Jill --[[User:Z3265772|z3265772]] 23:59, 1 September 2010 (UTC)

I've uploaded the first pic... I hope it's ok and if I did the layers wrongly please tell me so I can edit... also how do you do referencing that is not from pubmed journals?--[[User:Z3224500|Jenny]] 23:18, 1 September 2010 (UTC)

Hi Jenny, are you doing the drawn figure still? would you possibly be able to upload it before thursday? i have updated references for my section :) - Jill --[[User:Z3265772|z3265772]] 08:52, 1 September 2010 (UTC)

--[[User:S8600021|Mark Hill]] 00:49, 31 August 2010 (UTC) I have emailed your missing team member , but have not had a response yet. Your should continue to work on the project together as best you can. It seems to be progressing, though I did ask you to update your reference format and I do not see a student drawn figure. You need to have this updated before this weeks lab when I will be reviewing all projects.

Hi Jill, I'm working on it :) by the way have you heard from the other team member? Oh and I'll be drawing pictures for both the transcervical and transabdominal techniques..--[[User:Z3224500|Jenny Huang]] 07:46, 30 August 2010 (UTC)

Hi guys, only two weeks to go, we really need to do some more work, the editing at the end will be the hardest, so the sooner we finish, the easier it will be. - Jill--[[User:Z3265772|z3265772]] 23:46, 29 August 2010 (UTC)

Can we incorporate some sort of timeline? what do you think? maybe we can do a timeline of embryo development and note the time that CVS is done - Jill --[[User:Z3265772|z3265772]] 00:57, 26 August 2010 (UTC)

Mark has kindly shown us how to reference, ill try to sort that out tonight or tomorrow - Jill --[[User:Z3265772|z3265772]] 23:16, 25 August 2010 (UTC)

Ive just discovered, you can use almost any picture on wiki, the copyrights have usually expired, which is why wiki can use them, just search CVS on wiki and if there is a picture you like, check the copyright and copy away!! :D -Jill --[[User:Z3265772|z3265772]] 01:05, 25 August 2010 (UTC)

Hi guys, please feel free to edit any work i have done, or add to it, or even suggest to me on this page what to add. what i have put up so far really is a rough draft and will be trying to add to it later anyway :) -Jill --[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

{{Template:Projects10MHtalk}}

Hi guys, we need to get on top of this, its due for peer assessment in 3 weeks! Im going to do related research. does anyone want to do the drawing? ill also try and get some more references and photos up, as Mark has suggested. If you want a picture, just email the website with the picture on it, thats what ive been doing, they are usually pretty good about it. let me know of any other ideas you guys might have - Jill --[[User:Z3265772|z3265772]] 09:50, 23 August 2010 (UTC)

--[[User:S8600021|Mark Hill]] 04:35, 23 August 2010 (UTC) OK there are a few references here, but you will need more than these few and there should be some related images.

Link for group assessment criteria: [[2010_Lab_1#Group_Assessment_Criteria|group assessment criteria]] - Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

For current associated research:

http://onlinelibrary.wiley.com/doi/10.1002/pd.2410/abstract

http://www.ncbi.nlm.nih.gov/pubmed/11263542

http://www.ncbi.nlm.nih.gov/pubmed/19683693

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T7V-4BWVXPY-F9&_user=10&_coverDate=03%2F31%2F1994&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1427646674&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a3c3f2d47ad01c562a3baea8c60a48bc

http://www.informaworld.com/smpp/content~db=all~content=a913951525

http://www.escardiocontent.org/periodicals/ejcpr/article/S0002-9378%2807%2900305-5/abstract

http://humrep.oxfordjournals.org/cgi/content/abstract/3/6/811

- Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

Hi guys, i put up the link for Search Pubmed for our topic, did we want to assign ourselves a role to do or just see how the page goes? i thought maybe we could find a page that we like and follow a similar format, that way we know what our page will look like and can follow a layout as we go. -Jill --[[User:Z3265772|z3265772]] 01:12, 9 August 2010 (UTC)

also, see this web page http://www.cdc.gov/mmwr/preview/mmwrhtml/00038393.htm Jill --[[User:Z3265772|z3265772]] 11:16, 9 August 2010 (UTC)

project outline:

1. Intro

2. historic background

3. current associated research

4. simplified description of technique

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

5. student drawn figure or animation

6. reference list

7. glossary

8. external links

-Jill --[[User:Z3265772|z3265772]] 03:05, 11 August 2010 (UTC)

Can anyone tell me how to paste a picture from an outside source? i cant seem to figure it out. thanks :)
-Jill --[[User:Z3265772|z3265772]] 05:03, 11 August 2010 (UTC)

dont worry, i figured it out :)

i think we should put the references list on this page to begin with to make sure we dont double up
- Jill --[[User:Z3265772|z3265772]] 05:31, 11 August 2010 (UTC)

Hey guys sorry for the delay in replies. I see you have made a contribution to the topic already :) By the way, where did you find the project outline criteria? Oh and if you don't mind I can do research on the description of technique and current research. Feel free to contribute :) oh and any ideas on how to work on the drawings? --[[User:Z3224500|Jenny Huang]] 15:29, 11 August 2010 (UTC)

Hello guys,

So I found some journal articles that is of interest especially this one: http://apps.who.int/rhl/reviews/langs/CD003252.pdf which is long and has extensive information on the topic..
So I'll be editing my section in word and will be posting some info on technique in the future.

Btw here are some other articles that are of interest that can be accessed through unsw sirius:

http://linkinghub.elsevier.com/retrieve/pii/S0889854505702916

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

http://journals.lww.com/co-obgyn/Abstract/2005/04000/Chorionic_villus_sampling_and_amniocentesis.16.aspx

Complications:

http://journals.lww.com/greenjournal/Abstract/2007/09000/Procedure_Related_Complications_of_Amniocentesis.24.aspx

http://journals.lww.com/greenjournal/Abstract/2008/10000/Evaluating_the_Rate_and_Risk_Factors_for_Fetal.12.aspx

I'll be adding more once I find some that are useful..

Oh and about the topic headings are we just going to use the ones in the assesment criteria?

--[[User:Z3224500|z3224500]] 15:03, 24 August 2010 (UTC)

Hey Jenny!! i think its a great idea to use more headings, add as many as you like/can think of, i just cant think of any more. i think the assessment criteria is just the bare minimum we have to do, so please add more! Also, can we add the new discussion posts to the top of the page? so we dont have to scroll to the bottom every time? what do you think? (it says up the top of this page to add newer material at the top, just wondering what you thought). i really like the articles you have found too :) see you tomorrow
- Jill --[[User:Z3265772|z3265772]] 00:29, 25 August 2010 (UTC)

2010 Group Project 2

2010-09-30T00:23:01Z

Z3224500: /* Description of technique */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=
[[File:Gray37.png|right|thumb|280px|Sample is taken from the chorionic villi]]
[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. Between 10-12 weeks of pregnancy, the developing gestational sac is composed of a thick, outer chorionic membrane surrounding the amniotic cavity, a thin amniotic membrane and the chorionic cavity. The chorionic villi have now degenerated over most of the outer membrane, forming the chorion laeve, and the remaining villi fuses and embeds loosely into the decidua basalis. This forms the chorion frondosum, which will ultimately become the placenta. At this stage, the villi float freely in the blood of the intervillus space. Each villi is branched, and is composed of an outer syncytiotrophoblast and an inner cytotrophoblast layer. Within the centre of each villus is a mesenchymal core which contain capillaries carrying fetal blood. In CVS, usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.<ref>Jenkins, T.M, Wapner, R.J, 1999. First trimester prenatal diagnosis: Chorionic villus sampling. Seminars in Perinatology. pp403-413.</ref>

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors.<ref>Cica. N., 1998. Abortion Law in Australia. Parliament of Australia, Parliamentary Library. Accessed September 29. 2010. <http://www.aph.gov.au/library/pubs/rp/1998-99/99rp01.htm></ref> If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

Talk:2010 Group Project 2

2010-09-30T00:08:57Z

Z3224500:

Umm.. I'm not sure about that, because the sources I found mosaicism on had it in their "limitations" heading... --[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)--[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)

Hey Jenny, do you think Mosaicism should be in the abnormalities found by CVS section? a few people have commented that its a bit confusing what the test detects and the risks associated with testing. i think Mosaicism is more under the heading of what cvs detects --[[User:Z3265772|z3265772]] 04:16, 23 September 2010 (UTC)

hey jill,
group 6 here, you may use our picture

--[[User:Z3254433|z3254433]] 09:07, 26 September 2010 (UTC)

===to fix===

'''Begin''' by collating the comments.
* What are the common criticisms?
* What were the best aspects identified within your project?
* What errors, typos, missing references were identified?
* Were there contributions from individual group members that were identified as good or poor parts of the overall project?

'''Then''' work on the changes.
* Develop priorities.
* Divide the changes and corrections between group members.
* Are there additional changes that should be made that were not identified by peer assessment.

'''Jill:'''

abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? comparative genomics, Improvements?

future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether

DONE move glossary above references so you dont have to scroll all the way down to read them

DONE table comparing other techniques

DONE got confused between the risks of this test and what it predicted (this will be clear in the above table)

DONE -it didn't state that the test was invasive in intro (table)

DONE -All spelling amd grammar - some more editing of spelling is required

DONE "abnormalities found by CVS" section towards the top of the page coz I got confused between the risks of this test and what it predicted

DONE -link or a reference to the brief time line where you state the names of the authors

DONE -The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed

DONE -I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources

DONE -a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work

DONE - it would be that you put the advantages/disadvantages of CVS over other techniques in a table.

'''Jenny:'''

flowchart or more pictures of procedure

DONE clarify what hypertension is in the hypertensive disorders of pregnancy section

outcomes + ethics,

DONE Are the transabdominal and the transcervical pictures the student-drawn ones? put up in discussion that you drew them and you give permission for re-use - Jenny, ive done this for you, all you need to do is edit and add your student number, -Jill

DONE elaborate on procedure eg what cells are being taken etc and stages of chorionic villus in embryology

DONE Spelling and grammar, - Jenny, ive gone through the page and edited the spelling mistakes i could find, could you please do the same incase ive missed any? and double check the sections you are about to write? Thanks :) - Jill --[[User:Z3265772|z3265772]] 00:33, 24 September 2010 (UTC)

The current research section could be put more into point form to make it more inviting to read - not sure if you want to do this, i think its ok as it is, maybe just delete this suggestion? or add pictures of people researching? haha

----

==Peer Review==

'''Please note!''' when posting your peer review, we only have two group members. the other one dropped out. Thanks :)

--[[User:Z3129413]] 16:29, 22 September 2010 (UTC)
I love those old timey pencil medical pictures and so for me this was really great, what instantly nailed the whole positive immediate impression was 'Reasons for getting chorionic villus sampling etc etc' right there at the beginning. Why would I get one? thanks very much. Perhaps a darker font would make it even better. Historical back ground is really good and technique pictures are of high standard. The table presentation of abnormalities found and ratios is such an effective way of portraying this information.

A few Q's with the hypertension cvs topic,
Is there a normally expected percent of women in a large population to develop hypertensive disorders, just for perspective? CVS would not lower incidences of such surely (9098 pop, 2.7% to 7.1% control). 138 study size seems a bit low, is result really much more significant? However I did understand that CVS was more risk prone than amniocentesis for pre eclampsia and gestational hypertension.
This project is well on track.

Group 2: Your project is very impressive in content as well as organisation. The most notable thing for me was the wide use of pictures which must have taken a lot of time and effort to source. They definitely create an engaging page especially in conjunction with the use of tables and clear subheadings. The structure you have used is very effective as it allows your information to be scientific and thorough but at the same time it is concise and easy to navigate. I felt like i got an extensive overview of CVS after having read your page and the use of pictures and subheadings kept it from being a chore. I felt the history and abnormalities sections were particularly interesting. I also appreciate how you have seemed to approach this topic from all angles and not just a one-sided, all current and positive viewpoint. To improve your page perhaps you could explore the future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether. Either way your page is probably up to standard as it is and it is obvious that you have worked hard at it. Job well done.
--[[User:Z3293029|z3293029]] 14:38, 22 September 2010 (UTC)

Group 2: fantastic use of images, it definitely worked to your advantage in engaging your audience's attention. Over all the language used is relatively easy to follow yet informative. As someone has already mentioned, some more editing of spelling is required. The amount of attention to detail is evident in the references which are from a range of sources so well done. I particularly liked that the page covered accuracy and limitations of the diagnostic procedure. Something that lacked clarity in a few other groups. Good use of the table covering the abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? Improvements?
Just an idea. Well done overall. --z3241780 13:40, 22 September 2010 (UTC)

'''GROUP 2: Chorionic Villi Sampling'''

This page caught my attention as soon as I saw it and that made me want to read on and thus learn about Chorionic Villi Sampling. A lot of research has gone into this assignment and it’s evident in the information presented as its precise which also helps capture the readers. The amount of research is also evident in the long list of references. The webpage is actually extremely informative covering pretty much every aspect of the pre-natal diagnostic techniques. Your webpage has the most pictures and this helps it stand out as one of the best project pages. I really, really like the formatting and the tables. The images break up the information so you’re never overloaded with the amount of text. The only bit of criticism is spelling but this is extremely minor as you’ll pick up on the spelling mistakes when you go over the page. The language in is the right mixture of scientific language meaning that even people without a scientific background can understand the CVS. Great job guys you really can’t tell that only two people are in this group. It’s extremely good!!! I also really like the first picture you have, gives a page a really good feel to it.

--[[User:Z3252635|z3252635]] 13:20, 22 September 2010 (UTC)

Hi guys!

You have found so many great pictures! Your page looks amazing. I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources. Your timeline was great too; I really like how you put up the concise timeline and then expanded a bit on the major developments afterwards. Are the transabdominal and the transcervical pictures the student-drawn ones? If so, well done! They’re really clear and beautifully done, but you should probably label them as student drawn and put in the copyright statement. If I could suggest something, it would be that you put the advantages/disadvantages of CVS over other techniques in a table. Otherwise, your page is really easy to read, and again has brilliant visuals – great job!--[[User:Z3252833|z3252833]] 12:42, 22 September 2010 (UTC)

CVS.

Group 2, your project is looking great, the first thing i noticed when reading it is that there is lots of detail which shows a great depth of research has gone into it, which is supported by your reference list. Another thing is the amount of pictures which support the information and break it up to make it easier to take in so much information at once. The disorders table provides great detail and makes it interesting with the pictures.

What could be improved: You could put the advantages/disadvantages into a table form to make it even easier to understand. The reasons to use this technique could be slotted into the procedure section instead of the introduction maybe as it shows who is eligible for the procedure. The current research section could be put more into point form to make it more inviting to read. But overall really great project.

--[[User:Z3292208|z3292208]] 08:55, 22 September 2010 (UTC)

This project is extremely well done. It seems a great effort has gone into proper referencing which also gives the impression of a thoughtful attempt. The balance of information mediums is great and the logical flow of ideas when reading through each section is perfect.
Suggestion: possibly more pictures or a flowchart of the procedure itself?

Well done :)

--[[User:Z3254753|z3254753]] 16:55, 21 September 2010 (UTC)

Group 2- This project had tons of photos which is super great because its much easier to follow... Most of the point made is supported with pictures ..definetly provided me a better understanding of CVS ..I agree with what others have mentioned its very informative and especially with just 2 team members .. fantastic work

what could be improved = a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work ..--[[User:Z3305561|Navneet Ahuja]] 12:53, 21 September 2010 (UTC)

Group project 2: chorionic villus sampling

This group had great images and the page layout was good too especially the tables which simplified the information and made it easier to read. The information presented was very informative, scientific, and all the key concepts were covered on the topic. The project had a very impressive reference list, and it did help in my understanding of this prenatal diagnostic technique.

What could be improved?
I did find a spelling mistake under the heading Results and Accuracy were you have written “maybe” instead of “baby”, so maybe proof read the assignment to pick up on any other possible spelling or grammatical errors, other than that well done.

--[[User:Z3254433|z3254433]] 07:15, 20 September 2010 (UTC)

This project was highly informative about CVS. It contained a lot of information in which it shows that a lot of research has gone into it. Everything has been covered like, what the test predicts and what risks are associated with this test. It was very scientific, yet easy to understand at a non-scientific level. I liked the external links how it directed me straight to a page of different articles about CVS.

What could be improved is maybe placing the "abnormalities found by CVS" section towards the top of the page, because i was a bit unsure on what this test predicted in the first place. I got confused between the risks of this test and what it predicted. But I managed to understand it all once all read through. Also, a definition of a "cannula" may be helpful in the glossary too, i wasn't sure what that exactly was.

--[[User:Z3291079|z3291079]] 02:48, 21 September 2010 (UTC)

This project provides a clear understanding of the key information regarding CVS, such as how it is carried out, the risks and benfits of CVS, what it is used for as well as future research. I have find the pictures to be of a great help in explaining the procedure of CVS.

One think I did notice was that, it didn't state that the test was invasive until you figure it out when you look at the pictures in the procedures. I think stating that in the introduction would make it clearer for readers to follow on with the information this projects provides having that knowledge in mind at the start.

--[[User:Z3216889|3216889]] 12:13, 22 September 2010 (UTC)

This web page is definitely one of my favorites. The information that you have provided is exceptional; the reference list is indicative of your extensive research. The table of deformities was a stand out for me as it was very well set out and was a effective break from the text. You also used excellent external links that were very well placed within the web page. A slight improvement would be to include a link or a reference to the brief time line where you state the names of the authors, and as previously mentioned, reference the statistics that you have included. Other than that, I applaud you for a job well done!--[[User:Z3252083|z3252083]] 12:22, 22 September 2010 (UTC)

--Group 2 Chronic villus sampling
This webpage shows that the group was very thorough in the research due to the amount of detail that has gone into it and its many links. The layout is very well set out which helps someone understand it if he/she has no previous knowledge of the concept. The use of pictures and diagrams were done well as it broke the page up making it very easy to read and take in the information. The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed. That’s all guys and well done considering you only had 2 people working on it.

--[[User:Z3290040|3290040]] 10:19, 22 September 2010 (UTC)

----

----

===group discussion===

I agree the page feels more "in order" now. yeh... its tough trying to find more information. I guess i'll expand on maybe on some of the abnormalities? I was thinking we can get pictures of the several diseases but it will probably be a little difficult due to copyright? hmm if i get new ideas from now until tommorrow i'll definately add more stuff in --[[User:Z3224500|Jenny Huang]] 06:38, 15 September 2010 (UTC)

Hey Jenny, i changed the order of the page around, i think it makes more sense now, before it didnt really flow from one section to the next, i think its a bit better, i tried to do it on this order, Intro, history, procedure, results, risks, advantages. that order seems to be how most wiki pages are set up, and how mark sets up his pages. what do you think? -Jill --[[User:Z3265772|z3265772]] 02:14, 15 September 2010 (UTC)

i think i searched prenatal diagnosis in the search box on the left, and mark has made a prenatal diagnosis page. the prenatal diagnosis terms were on that. ive been looking at last years pages, and they have so much content, but there just isnt that much information on CVS. theres only so much you can write about it. i guess we need to start thinking outside the box and adding general prenatal stuff on here too. thats why i thought maybe another table with a timeline of other techniques on it. ? ill just do it and see how it looks... -Jill --[[User:Z3265772|z3265772]] 01:47, 15 September 2010 (UTC)

hmm good idea.. btw what article did you find the terms for the prenatal diagnosis? should i incorporate that in the results section? --[[User:Z3224500|Jenny Huang]] 15:19, 14 September 2010 (UTC)

maybe we could also do ethical issues? -Jill --[[User:Z3265772|z3265772]] 12:35, 14 September 2010 (UTC)

Just an idea if we wanted to add more to the page, we could do another table, with the different diagnostic techniques used - eg ultrasound, AFP, amniocentesis and CVS etc and do a timeline with when each technique can be used, what it can test for, and how invasive it is. i know its not directly CVS, but it will give a good overview of the advantages and disadvantages etc. and im running out of ideas of what else we can have on here. can you think of anything else? -Jill --[[User:Z3265772|z3265772]] 12:30, 14 September 2010 (UTC)

Found out its due thurs, Sorry!! im doing malformations now, but we definitely need to add more content, last years pages had over 600 revisions, we only have 200. So add whatever you think we could do to improve the page. Thanks for your help over the weekend, i did feel alone in creating the page! Looks great now though! Maybe we could look at last years pages and see what we like about them, and maybe get some ideas on how to add to our page. im trying to put alot of effort in as its worth 20% of our final mark :) ive also added to the malformations part, ill keep doing that. Thanks!! -Jill --[[User:Z3265772|z3265772]] 02:24, 13 September 2010 (UTC)

Hey can't make it to lecture today.. but if its due for peer assesment today/this week, what suggestions do you think we can improve on? hmm also whos doing the part on malformations? --[[User:Z3224500|Jenny Huang]] 23:07, 12 September 2010 (UTC)

yeah good question.. ill see if i can find something more recent and let you know. i guess it would be. also, hope you dont mind, i put some of your references in, and added some pictures :) -Jill --[[User:Z3265772|z3265772]] 13:00, 12 September 2010 (UTC)

Hey for the section on malformations in current research, would it be limb defects? the articles I found were mostly from the 1990s so I'm not sure if I should use..--[[User:Z3224500|Jenny Huang]] 12:49, 12 September 2010 (UTC)

Yay it looks neat!!!glad you figured out how to fix the formatting.. It was rather confusing before haha. SOrry if it seems like you are doing most of the work :( I'll add to the current research to lighten off your load.i'll be working on it most of the weekend--[[User:Z3224500|Jenny Huang]] 16:39, 10 September 2010 (UTC)

I made a table!! it took AGES but it looks good :) we probably need to spread everything out a bit, it looks a bit crowded, but getting there! i separated the risks from current research :)- Jill --[[User:Z3265772|z3265772]] 12:03, 10 September 2010 (UTC)

Hmm it didn't take that long.. btw I've already done it but I haven't uploaded it yet but I'll do so now... hmm by the way should the heading "risks" be separate from the "current assosciated research" heading?--[[User:Z3224500|Jenny Huang]] 02:53, 10 September 2010 (UTC)

Hey! Did it take long to do the drawing for the transabdominal technique? i was thinking we could do a second one the same for transcervical. what do you think? - Jill --[[User:Z3265772|z3265772]] 02:09, 10 September 2010 (UTC)

Im pretty sure its due monday for peer assessment, thats what it says in the course guide. did he say it was due thurs in the lab last week? hope its due thurs! that would be awesome! - Jill --[[User:Z3265772|z3265772]] 12:00, 9 September 2010 (UTC)

Hey Jill, wow only 4 days! I was mistaken that it was due next thursday. But don't wrry, I'll have the whole weekend to finish up ;)--[[User:Z3224500|Jenny Huang]] 08:30, 9 September 2010 (UTC)

Hi! Ive used a reference that is not from pub med, so you can copy that to use references that arent in pub med. :) only 4 days till its due! - Jill --[[User:Z3265772|z3265772]] 01:29, 9 September 2010 (UTC)

some pictures we can use, this first one is Primary chorionic villi, the second picture is secondary chorionic villi, these may be helpful when describing the technique -Jill --[[User:Z3265772|z3265772]] 09:52, 7 September 2010 (UTC)

[[File:Gray36.png|left|400 px]]

[[File:Gray37.png|left|400 px]]

Hmm so basically we do the peer review the week after mid sem break until the 23rd of september, and we paste both the review on the groups page and on your own page... also apparently the other student discontinued the course so its just us doing the project now =S --[[User:Z3224500|Jenny Huang]] 03:02, 2 September 2010 (UTC)

Yay!! looks awesome!! Sorry i couldnt be there today, could you let me know what Mark says? thanks :) - Jill --[[User:Z3265772|z3265772]] 23:59, 1 September 2010 (UTC)

I've uploaded the first pic... I hope it's ok and if I did the layers wrongly please tell me so I can edit... also how do you do referencing that is not from pubmed journals?--[[User:Z3224500|Jenny]] 23:18, 1 September 2010 (UTC)

Hi Jenny, are you doing the drawn figure still? would you possibly be able to upload it before thursday? i have updated references for my section :) - Jill --[[User:Z3265772|z3265772]] 08:52, 1 September 2010 (UTC)

--[[User:S8600021|Mark Hill]] 00:49, 31 August 2010 (UTC) I have emailed your missing team member , but have not had a response yet. Your should continue to work on the project together as best you can. It seems to be progressing, though I did ask you to update your reference format and I do not see a student drawn figure. You need to have this updated before this weeks lab when I will be reviewing all projects.

Hi Jill, I'm working on it :) by the way have you heard from the other team member? Oh and I'll be drawing pictures for both the transcervical and transabdominal techniques..--[[User:Z3224500|Jenny Huang]] 07:46, 30 August 2010 (UTC)

Hi guys, only two weeks to go, we really need to do some more work, the editing at the end will be the hardest, so the sooner we finish, the easier it will be. - Jill--[[User:Z3265772|z3265772]] 23:46, 29 August 2010 (UTC)

Can we incorporate some sort of timeline? what do you think? maybe we can do a timeline of embryo development and note the time that CVS is done - Jill --[[User:Z3265772|z3265772]] 00:57, 26 August 2010 (UTC)

Mark has kindly shown us how to reference, ill try to sort that out tonight or tomorrow - Jill --[[User:Z3265772|z3265772]] 23:16, 25 August 2010 (UTC)

Ive just discovered, you can use almost any picture on wiki, the copyrights have usually expired, which is why wiki can use them, just search CVS on wiki and if there is a picture you like, check the copyright and copy away!! :D -Jill --[[User:Z3265772|z3265772]] 01:05, 25 August 2010 (UTC)

Hi guys, please feel free to edit any work i have done, or add to it, or even suggest to me on this page what to add. what i have put up so far really is a rough draft and will be trying to add to it later anyway :) -Jill --[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

{{Template:Projects10MHtalk}}

Hi guys, we need to get on top of this, its due for peer assessment in 3 weeks! Im going to do related research. does anyone want to do the drawing? ill also try and get some more references and photos up, as Mark has suggested. If you want a picture, just email the website with the picture on it, thats what ive been doing, they are usually pretty good about it. let me know of any other ideas you guys might have - Jill --[[User:Z3265772|z3265772]] 09:50, 23 August 2010 (UTC)

--[[User:S8600021|Mark Hill]] 04:35, 23 August 2010 (UTC) OK there are a few references here, but you will need more than these few and there should be some related images.

Link for group assessment criteria: [[2010_Lab_1#Group_Assessment_Criteria|group assessment criteria]] - Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

For current associated research:

http://onlinelibrary.wiley.com/doi/10.1002/pd.2410/abstract

http://www.ncbi.nlm.nih.gov/pubmed/11263542

http://www.ncbi.nlm.nih.gov/pubmed/19683693

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T7V-4BWVXPY-F9&_user=10&_coverDate=03%2F31%2F1994&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1427646674&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a3c3f2d47ad01c562a3baea8c60a48bc

http://www.informaworld.com/smpp/content~db=all~content=a913951525

http://www.escardiocontent.org/periodicals/ejcpr/article/S0002-9378%2807%2900305-5/abstract

http://humrep.oxfordjournals.org/cgi/content/abstract/3/6/811

- Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

Hi guys, i put up the link for Search Pubmed for our topic, did we want to assign ourselves a role to do or just see how the page goes? i thought maybe we could find a page that we like and follow a similar format, that way we know what our page will look like and can follow a layout as we go. -Jill --[[User:Z3265772|z3265772]] 01:12, 9 August 2010 (UTC)

also, see this web page http://www.cdc.gov/mmwr/preview/mmwrhtml/00038393.htm Jill --[[User:Z3265772|z3265772]] 11:16, 9 August 2010 (UTC)

project outline:

1. Intro

2. historic background

3. current associated research

4. simplified description of technique

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

5. student drawn figure or animation

6. reference list

7. glossary

8. external links

-Jill --[[User:Z3265772|z3265772]] 03:05, 11 August 2010 (UTC)

Can anyone tell me how to paste a picture from an outside source? i cant seem to figure it out. thanks :)
-Jill --[[User:Z3265772|z3265772]] 05:03, 11 August 2010 (UTC)

dont worry, i figured it out :)

i think we should put the references list on this page to begin with to make sure we dont double up
- Jill --[[User:Z3265772|z3265772]] 05:31, 11 August 2010 (UTC)

Hey guys sorry for the delay in replies. I see you have made a contribution to the topic already :) By the way, where did you find the project outline criteria? Oh and if you don't mind I can do research on the description of technique and current research. Feel free to contribute :) oh and any ideas on how to work on the drawings? --[[User:Z3224500|Jenny Huang]] 15:29, 11 August 2010 (UTC)

Hello guys,

So I found some journal articles that is of interest especially this one: http://apps.who.int/rhl/reviews/langs/CD003252.pdf which is long and has extensive information on the topic..
So I'll be editing my section in word and will be posting some info on technique in the future.

Btw here are some other articles that are of interest that can be accessed through unsw sirius:

http://linkinghub.elsevier.com/retrieve/pii/S0889854505702916

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

http://journals.lww.com/co-obgyn/Abstract/2005/04000/Chorionic_villus_sampling_and_amniocentesis.16.aspx

Complications:

http://journals.lww.com/greenjournal/Abstract/2007/09000/Procedure_Related_Complications_of_Amniocentesis.24.aspx

http://journals.lww.com/greenjournal/Abstract/2008/10000/Evaluating_the_Rate_and_Risk_Factors_for_Fetal.12.aspx

I'll be adding more once I find some that are useful..

Oh and about the topic headings are we just going to use the ones in the assesment criteria?

--[[User:Z3224500|z3224500]] 15:03, 24 August 2010 (UTC)

Hey Jenny!! i think its a great idea to use more headings, add as many as you like/can think of, i just cant think of any more. i think the assessment criteria is just the bare minimum we have to do, so please add more! Also, can we add the new discussion posts to the top of the page? so we dont have to scroll to the bottom every time? what do you think? (it says up the top of this page to add newer material at the top, just wondering what you thought). i really like the articles you have found too :) see you tomorrow
- Jill --[[User:Z3265772|z3265772]] 00:29, 25 August 2010 (UTC)

2010 Group Project 2

2010-09-30T00:08:10Z

Z3224500: /* Description of technique */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=
[[File:Gray37.png|right|thumb|280px|Sample is taken from the chorionic villi]]
[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. Between 10-12 weeks of pregnancy, the developing gestational sac is composed of a thick, outer chorionic membrane surrounding the amniotic cavity, a thin amniotic membrane and the chorionic cavity. The chorionic villi have now degenerated over most of the outer membrane, forming the chorion laeve, and the remaining villi fuses and embeds loosely into the decidua basalis. This forms the chorion frondosum, which will ultimately become the placenta. At this stage, the villi float freely in the blood of the intervillus space. Each villi is branched, and is composed of an outer syncytiotrophoblast and an inner cytotrophoblast layer. Within the centre of each villus is a mesenchymal core which contain capillaries carrying fetal blood. In CVS, usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors.<ref>Cica. N., 1998. Abortion Law in Australia. Parliament of Australia, Parliamentary Library. Accessed September 29. 2010. <http://www.aph.gov.au/library/pubs/rp/1998-99/99rp01.htm></ref> If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-30T00:06:20Z

Z3224500: /* Description of technique */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=
[[File:Gray37.png|right|thumb|280px|Sample is taken from the chorionic villi]]
[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. Between 10-12 weeks of pregnancy, the developing gestational sac is composed of a thick, outer chorionic membrane surrounding the amniotic cavity, a thin The chorionic membrane and the chorionic cavity. The chorionic villi have now degenerated over most of the outer membrane, forming the chorion laeve, and the remaining villi fuses and embeds loosely into the decidua basalis. This forms the chorion frondosum, which will ultimately become the placenta. At this stage, the villi float freely in the blood of the intervillus space. Each villi is branched, and is composed of an outer syncytiotrophoblast and an inner cytotrophoblast layer. Within the centre of each villus is a mesenchymal core which contain capillaries carrying fetal blood. In CVS, usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors.<ref>Cica. N., 1998. Abortion Law in Australia. Parliament of Australia, Parliamentary Library. Accessed September 29. 2010. <http://www.aph.gov.au/library/pubs/rp/1998-99/99rp01.htm></ref> If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T21:11:37Z

Z3224500: /* Description of technique */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=
[[File:Gray37.png|right|thumb|280px|Sample is taken from the chorionic villi]]
[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. The chorionic membrane is the outer sac which surrounds the developing fetus. Usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors.<ref>Cica. N., 1998. Abortion Law in Australia. Parliament of Australia, Parliamentary Library. Accessed September 29. 2010. <http://www.aph.gov.au/library/pubs/rp/1998-99/99rp01.htm></ref> If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T13:22:37Z

Z3224500: /* Outcomes */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. The chorionic membrane is the outer sac which surrounds the developing fetus. Usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors.<ref>Cica. N., 1998. Abortion Law in Australia. Parliament of Australia, Parliamentary Library. Accessed September 29. 2010. <http://www.aph.gov.au/library/pubs/rp/1998-99/99rp01.htm></ref> If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T13:00:04Z

Z3224500: /* Description of technique */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. The chorionic membrane is the outer sac which surrounds the developing fetus. Usually samples of both cells lines (cytotrophoblasts and mesenchymal cells) are obtained. Chromosomal analysis of these cell lines can be performed by means of direct preparations, short-term cultures (cytotrophoblasts), or long-term cultures (mesenchymal cells) of the chorionic villi.

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T12:56:35Z

Z3224500: /* Description of technique */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

The CVS procedure involves taking a sample of the chorion frondosum — the part of the chorionic membrane containing the villi. The chorionic membrane is the outer sac which surrounds the developing fetus.

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T12:36:54Z

Z3224500: /* Treatment */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods can manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways. <ref><pubmed>18079549</pubmed></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T12:22:25Z

Z3224500: /* Treatment */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Cystic fibrosis'''

There is currently no cure for cystic fibrosis, but various treatment methods to manage the symptoms of lung and digestive problems, liver and gallbladder diseases and infertility. Digestive problems can be corrected by having a diet that is low in fat and high in protein, with vitamin supplements. Regular antibiotics are regularly prescribed to prevent and to treat lung infections, and mucolytics are needed to make the mucous less sticky. Other methods to dislodge and remove mucous is manual chest physiotherapy, where it consists of bronchial drainage done manually or mechanically. Manual drainage can be done by performing controlled breathing techniques or the chest is vibrated or clapped to dislodge the mucous out of the airways.

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T11:56:21Z

Z3224500: /* Treatment */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf></ref>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T11:53:22Z

Z3224500: /* Treatment */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect. Some of these management options for some of the defects will be discussed below.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.<Ref>Stewart, K. B., 2007. Trisomy 13 - Patau Syndrome. [Fact sheet] Centre for Genetics Education. Accessed 29 September, 2010. <http://www.genetics.com.au/pdf/factsheets/fs29.pdf>

'''Tay-sachs disease'''

The prognosis for babies with the condition is usually poor, with children living to the age of 4-5.<ref>National Institute of Neurological Disorders and Stroke. 2007. Tay-Sachs Disease Information Page. Accessed September 29, 2010. <http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm></ref> Therefore treatment for Tay-sachs disease is usually to help alleviate symptoms associated with the disease. Spasticity and siezures can be helped by administering anticonvulsants, while other supportive methods include respiratory care to keep the airway open and proper nutrition and hydration.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T11:28:44Z

Z3224500: /* Treatment */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

'''Trisomy 13'''

Since Trisomy 13 causes a range of serious complications like congenital heart disease and brain and spinal cord abnormalities, the survival rate is low, with a median survival time of 2.5 days. <ref><pubmed>11310997</pubmed></ref> Treatment is usually directed towards the specific symptoms that are present in the affected child, which differs to each individual. In some cases, treatment may include surgical procedures to correct cleft lip and palate, or surgery to correct heart defects. This will depend upon the severity and nature of the abnormalities and symptoms.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T11:09:49Z

Z3224500: /* Treatment */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities. Some individuals affected with cardiac and gastrointestinal problems may also need surgery soon after birth. Regular screening for vision problems, hearing, hypothyroidism, and other medical conditions should be performed.

Cognitive development can be assisted with physiotherapy and speech therapy for example. Since children with Down Syndrome can have speech problems due to their relatively small mouths and large tongue, speech therapy can help the child to communicate properly. Physical therapy is often needed since individuals with Down Syndrome have hypotonia (low muscle tone)which needs to be improved by developing motor skills.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T10:04:27Z

Z3224500: /* Treatment */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect.

'''Down Syndrome'''

Treatment and therapies for Down syndrome available include the physical, medical and cognitive problems associated with Down Syndrome. Medical treatment such as surgery or medications, while early intervention programs and therapies help babies and children achieve better quality of life. For example, children with Down Syndrome have a higher risk for having many conditions such as congenital heart defects, problems with the thyroid, muscles, joint, vision and hearing problems. Medications can be used to treat these different problems, such as if the thyroid is affected, a child will benefit from taking thyroid replacement hormones. Medications aim to control the symptoms and reduce the impact the condition will have on the baby. There is no medication that can cure chromosome abnormalities.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T09:43:30Z

Z3224500: /* Outcomes */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

===Treatment===

If the mother decides to continue on with the pregnancy, treatment options are necessary for the baby after birth to maintain the health and symptoms associated with a defect.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T09:07:51Z

Z3224500: /* Outcomes */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' ''(Note: Not applicable in this case due to CVS being performed at 10-12 weeks.)''This involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, it is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T09:04:15Z

Z3224500: /* Outcomes */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -'''(Note: Not applicable in this case because due to CVS being performed at 10-12 weeks.)Involves administration of a drug called mifepristone (RU486). Available for abortions earlier than 2-9 weeks, ''' It is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T08:59:24Z

Z3224500: /* Outcomes */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

Abortion is the termination of pregnancy, with the removal of the fetus and placenta from the uterus. In Australia, abortion laws vary by state and usually allow this up to a range of about 12 - 20 weeks into the pregnancy, on the grounds of fetal abnormalities, endangerment of the mother and other socio-economic factors. If the mother chooses to terminate the pregnancy, counselling is usually done to make sure the parents understand the issues and ethics surrounding abortion.
There are currently two ways to perform an abortion:

'''Surgical abortion -''' Also called suction aspiration, or suction currette, this is the most common procedure used for first trimester abortion(up to 12 weeks) The cervix is dilated, and a tube is inserted through the cervix and a suction removes the fetus and the placenta. A curette is then used to scrape the wall of the uterus to ensure any remains are not left inside. If later in pregnancy, other surgical techniques are used.

'''Medical abortion -''' Available for abortions earlier than 2-9 weeks, '''(which is not applicable in this case because CVS is performed 10-12 weeks)''' which involves administration of a drug called mifepristone (RU486). It is a low-risk and effective method instead of the surgical method earlier in pregnancy. Usage of the drug is available in many countries but is currently restricted in Australia.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-29T07:58:26Z

Z3224500: /* Outcomes */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|[[File:FetalFN.jpg|right|150 px]]
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

Since CVS is able to detect a variety of chromosome abnormalities, there is a chance that the baby may be affected with a defect. If the test results are normal however, this does not exclude other congenital defects and neural tube defects that can occur that can be detected by other prenatal diagnosis methods. IF the test result is positive and a defect is detected by CVS, the mother has several options available. One is to terminate the pregnancy and the other is to seek treatment after the baby is born. If the mother chooses to terminate the pregnancy, doctors have a responsibility to educate the mother and offer counseling.

Doctors should:

*Give parents information about the defect so that they can be prepared.
*Talk to parents about the baby's predicted quality of life.
*Should explain any procedures that will be done to the baby after he is born.
*Doctors should do their best to tell parents what the problem is and how serious it is.

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

Talk:2010 Group Project 2

2010-09-29T01:42:27Z

Z3224500:

Umm.. I'm not sure about that, because the sources I found mosaicism on had it in their "limitations" heading... --[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)--[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)

Hey Jenny, do you think Mosaicism should be in the abnormalities found by CVS section? a few people have commented that its a bit confusing what the test detects and the risks associated with testing. i think Mosaicism is more under the heading of what cvs detects --[[User:Z3265772|z3265772]] 04:16, 23 September 2010 (UTC)

hey jill,
group 6 here, you may use our picture

--[[User:Z3254433|z3254433]] 09:07, 26 September 2010 (UTC)

===to fix===

'''Begin''' by collating the comments.
* What are the common criticisms?
* What were the best aspects identified within your project?
* What errors, typos, missing references were identified?
* Were there contributions from individual group members that were identified as good or poor parts of the overall project?

'''Then''' work on the changes.
* Develop priorities.
* Divide the changes and corrections between group members.
* Are there additional changes that should be made that were not identified by peer assessment.

'''Jill:'''

abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? comparative genomics, Improvements?

future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether

DONE move glossary above references so you dont have to scroll all the way down to read them

DONE table comparing other techniques

DONE got confused between the risks of this test and what it predicted (this will be clear in the above table)

DONE -it didn't state that the test was invasive in intro (table)

DONE -All spelling amd grammar - some more editing of spelling is required

DONE "abnormalities found by CVS" section towards the top of the page coz I got confused between the risks of this test and what it predicted

DONE -link or a reference to the brief time line where you state the names of the authors

DONE -The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed

DONE -I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources

DONE -a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work

DONE - it would be that you put the advantages/disadvantages of CVS over other techniques in a table.

'''Jenny:'''

flowchart or more pictures of procedure

DONE clarify what hypertension is in the hypertensive disorders of pregnancy section

possibly more pictures or a flowchart of the procedure itself?

outcomes + ethics,

DONE Are the transabdominal and the transcervical pictures the student-drawn ones? put up in discussion that you drew them and you give permission for re-use - Jenny, ive done this for you, all you need to do is edit and add your student number, -Jill

elaborate on procedure eg what cells are being taken etc and stages of chorionic villus in embryology

DONE Spelling and grammar, - Jenny, ive gone through the page and edited the spelling mistakes i could find, could you please do the same incase ive missed any? and double check the sections you are about to write? Thanks :) - Jill --[[User:Z3265772|z3265772]] 00:33, 24 September 2010 (UTC)

The current research section could be put more into point form to make it more inviting to read - not sure if you want to do this, i think its ok as it is, maybe just delete this suggestion? or add pictures of people researching? haha

----

==Peer Review==

'''Please note!''' when posting your peer review, we only have two group members. the other one dropped out. Thanks :)

--[[User:Z3129413]] 16:29, 22 September 2010 (UTC)
I love those old timey pencil medical pictures and so for me this was really great, what instantly nailed the whole positive immediate impression was 'Reasons for getting chorionic villus sampling etc etc' right there at the beginning. Why would I get one? thanks very much. Perhaps a darker font would make it even better. Historical back ground is really good and technique pictures are of high standard. The table presentation of abnormalities found and ratios is such an effective way of portraying this information.

A few Q's with the hypertension cvs topic,
Is there a normally expected percent of women in a large population to develop hypertensive disorders, just for perspective? CVS would not lower incidences of such surely (9098 pop, 2.7% to 7.1% control). 138 study size seems a bit low, is result really much more significant? However I did understand that CVS was more risk prone than amniocentesis for pre eclampsia and gestational hypertension.
This project is well on track.

Group 2: Your project is very impressive in content as well as organisation. The most notable thing for me was the wide use of pictures which must have taken a lot of time and effort to source. They definitely create an engaging page especially in conjunction with the use of tables and clear subheadings. The structure you have used is very effective as it allows your information to be scientific and thorough but at the same time it is concise and easy to navigate. I felt like i got an extensive overview of CVS after having read your page and the use of pictures and subheadings kept it from being a chore. I felt the history and abnormalities sections were particularly interesting. I also appreciate how you have seemed to approach this topic from all angles and not just a one-sided, all current and positive viewpoint. To improve your page perhaps you could explore the future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether. Either way your page is probably up to standard as it is and it is obvious that you have worked hard at it. Job well done.
--[[User:Z3293029|z3293029]] 14:38, 22 September 2010 (UTC)

Group 2: fantastic use of images, it definitely worked to your advantage in engaging your audience's attention. Over all the language used is relatively easy to follow yet informative. As someone has already mentioned, some more editing of spelling is required. The amount of attention to detail is evident in the references which are from a range of sources so well done. I particularly liked that the page covered accuracy and limitations of the diagnostic procedure. Something that lacked clarity in a few other groups. Good use of the table covering the abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? Improvements?
Just an idea. Well done overall. --z3241780 13:40, 22 September 2010 (UTC)

'''GROUP 2: Chorionic Villi Sampling'''

This page caught my attention as soon as I saw it and that made me want to read on and thus learn about Chorionic Villi Sampling. A lot of research has gone into this assignment and it’s evident in the information presented as its precise which also helps capture the readers. The amount of research is also evident in the long list of references. The webpage is actually extremely informative covering pretty much every aspect of the pre-natal diagnostic techniques. Your webpage has the most pictures and this helps it stand out as one of the best project pages. I really, really like the formatting and the tables. The images break up the information so you’re never overloaded with the amount of text. The only bit of criticism is spelling but this is extremely minor as you’ll pick up on the spelling mistakes when you go over the page. The language in is the right mixture of scientific language meaning that even people without a scientific background can understand the CVS. Great job guys you really can’t tell that only two people are in this group. It’s extremely good!!! I also really like the first picture you have, gives a page a really good feel to it.

--[[User:Z3252635|z3252635]] 13:20, 22 September 2010 (UTC)

Hi guys!

You have found so many great pictures! Your page looks amazing. I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources. Your timeline was great too; I really like how you put up the concise timeline and then expanded a bit on the major developments afterwards. Are the transabdominal and the transcervical pictures the student-drawn ones? If so, well done! They’re really clear and beautifully done, but you should probably label them as student drawn and put in the copyright statement. If I could suggest something, it would be that you put the advantages/disadvantages of CVS over other techniques in a table. Otherwise, your page is really easy to read, and again has brilliant visuals – great job!--[[User:Z3252833|z3252833]] 12:42, 22 September 2010 (UTC)

CVS.

Group 2, your project is looking great, the first thing i noticed when reading it is that there is lots of detail which shows a great depth of research has gone into it, which is supported by your reference list. Another thing is the amount of pictures which support the information and break it up to make it easier to take in so much information at once. The disorders table provides great detail and makes it interesting with the pictures.

What could be improved: You could put the advantages/disadvantages into a table form to make it even easier to understand. The reasons to use this technique could be slotted into the procedure section instead of the introduction maybe as it shows who is eligible for the procedure. The current research section could be put more into point form to make it more inviting to read. But overall really great project.

--[[User:Z3292208|z3292208]] 08:55, 22 September 2010 (UTC)

This project is extremely well done. It seems a great effort has gone into proper referencing which also gives the impression of a thoughtful attempt. The balance of information mediums is great and the logical flow of ideas when reading through each section is perfect.
Suggestion: possibly more pictures or a flowchart of the procedure itself?

Well done :)

--[[User:Z3254753|z3254753]] 16:55, 21 September 2010 (UTC)

Group 2- This project had tons of photos which is super great because its much easier to follow... Most of the point made is supported with pictures ..definetly provided me a better understanding of CVS ..I agree with what others have mentioned its very informative and especially with just 2 team members .. fantastic work

what could be improved = a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work ..--[[User:Z3305561|Navneet Ahuja]] 12:53, 21 September 2010 (UTC)

Group project 2: chorionic villus sampling

This group had great images and the page layout was good too especially the tables which simplified the information and made it easier to read. The information presented was very informative, scientific, and all the key concepts were covered on the topic. The project had a very impressive reference list, and it did help in my understanding of this prenatal diagnostic technique.

What could be improved?
I did find a spelling mistake under the heading Results and Accuracy were you have written “maybe” instead of “baby”, so maybe proof read the assignment to pick up on any other possible spelling or grammatical errors, other than that well done.

--[[User:Z3254433|z3254433]] 07:15, 20 September 2010 (UTC)

This project was highly informative about CVS. It contained a lot of information in which it shows that a lot of research has gone into it. Everything has been covered like, what the test predicts and what risks are associated with this test. It was very scientific, yet easy to understand at a non-scientific level. I liked the external links how it directed me straight to a page of different articles about CVS.

What could be improved is maybe placing the "abnormalities found by CVS" section towards the top of the page, because i was a bit unsure on what this test predicted in the first place. I got confused between the risks of this test and what it predicted. But I managed to understand it all once all read through. Also, a definition of a "cannula" may be helpful in the glossary too, i wasn't sure what that exactly was.

--[[User:Z3291079|z3291079]] 02:48, 21 September 2010 (UTC)

This project provides a clear understanding of the key information regarding CVS, such as how it is carried out, the risks and benfits of CVS, what it is used for as well as future research. I have find the pictures to be of a great help in explaining the procedure of CVS.

One think I did notice was that, it didn't state that the test was invasive until you figure it out when you look at the pictures in the procedures. I think stating that in the introduction would make it clearer for readers to follow on with the information this projects provides having that knowledge in mind at the start.

--[[User:Z3216889|3216889]] 12:13, 22 September 2010 (UTC)

This web page is definitely one of my favorites. The information that you have provided is exceptional; the reference list is indicative of your extensive research. The table of deformities was a stand out for me as it was very well set out and was a effective break from the text. You also used excellent external links that were very well placed within the web page. A slight improvement would be to include a link or a reference to the brief time line where you state the names of the authors, and as previously mentioned, reference the statistics that you have included. Other than that, I applaud you for a job well done!--[[User:Z3252083|z3252083]] 12:22, 22 September 2010 (UTC)

--Group 2 Chronic villus sampling
This webpage shows that the group was very thorough in the research due to the amount of detail that has gone into it and its many links. The layout is very well set out which helps someone understand it if he/she has no previous knowledge of the concept. The use of pictures and diagrams were done well as it broke the page up making it very easy to read and take in the information. The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed. That’s all guys and well done considering you only had 2 people working on it.

--[[User:Z3290040|3290040]] 10:19, 22 September 2010 (UTC)

----

----

===group discussion===

I agree the page feels more "in order" now. yeh... its tough trying to find more information. I guess i'll expand on maybe on some of the abnormalities? I was thinking we can get pictures of the several diseases but it will probably be a little difficult due to copyright? hmm if i get new ideas from now until tommorrow i'll definately add more stuff in --[[User:Z3224500|Jenny Huang]] 06:38, 15 September 2010 (UTC)

Hey Jenny, i changed the order of the page around, i think it makes more sense now, before it didnt really flow from one section to the next, i think its a bit better, i tried to do it on this order, Intro, history, procedure, results, risks, advantages. that order seems to be how most wiki pages are set up, and how mark sets up his pages. what do you think? -Jill --[[User:Z3265772|z3265772]] 02:14, 15 September 2010 (UTC)

i think i searched prenatal diagnosis in the search box on the left, and mark has made a prenatal diagnosis page. the prenatal diagnosis terms were on that. ive been looking at last years pages, and they have so much content, but there just isnt that much information on CVS. theres only so much you can write about it. i guess we need to start thinking outside the box and adding general prenatal stuff on here too. thats why i thought maybe another table with a timeline of other techniques on it. ? ill just do it and see how it looks... -Jill --[[User:Z3265772|z3265772]] 01:47, 15 September 2010 (UTC)

hmm good idea.. btw what article did you find the terms for the prenatal diagnosis? should i incorporate that in the results section? --[[User:Z3224500|Jenny Huang]] 15:19, 14 September 2010 (UTC)

maybe we could also do ethical issues? -Jill --[[User:Z3265772|z3265772]] 12:35, 14 September 2010 (UTC)

Just an idea if we wanted to add more to the page, we could do another table, with the different diagnostic techniques used - eg ultrasound, AFP, amniocentesis and CVS etc and do a timeline with when each technique can be used, what it can test for, and how invasive it is. i know its not directly CVS, but it will give a good overview of the advantages and disadvantages etc. and im running out of ideas of what else we can have on here. can you think of anything else? -Jill --[[User:Z3265772|z3265772]] 12:30, 14 September 2010 (UTC)

Found out its due thurs, Sorry!! im doing malformations now, but we definitely need to add more content, last years pages had over 600 revisions, we only have 200. So add whatever you think we could do to improve the page. Thanks for your help over the weekend, i did feel alone in creating the page! Looks great now though! Maybe we could look at last years pages and see what we like about them, and maybe get some ideas on how to add to our page. im trying to put alot of effort in as its worth 20% of our final mark :) ive also added to the malformations part, ill keep doing that. Thanks!! -Jill --[[User:Z3265772|z3265772]] 02:24, 13 September 2010 (UTC)

Hey can't make it to lecture today.. but if its due for peer assesment today/this week, what suggestions do you think we can improve on? hmm also whos doing the part on malformations? --[[User:Z3224500|Jenny Huang]] 23:07, 12 September 2010 (UTC)

yeah good question.. ill see if i can find something more recent and let you know. i guess it would be. also, hope you dont mind, i put some of your references in, and added some pictures :) -Jill --[[User:Z3265772|z3265772]] 13:00, 12 September 2010 (UTC)

Hey for the section on malformations in current research, would it be limb defects? the articles I found were mostly from the 1990s so I'm not sure if I should use..--[[User:Z3224500|Jenny Huang]] 12:49, 12 September 2010 (UTC)

Yay it looks neat!!!glad you figured out how to fix the formatting.. It was rather confusing before haha. SOrry if it seems like you are doing most of the work :( I'll add to the current research to lighten off your load.i'll be working on it most of the weekend--[[User:Z3224500|Jenny Huang]] 16:39, 10 September 2010 (UTC)

I made a table!! it took AGES but it looks good :) we probably need to spread everything out a bit, it looks a bit crowded, but getting there! i separated the risks from current research :)- Jill --[[User:Z3265772|z3265772]] 12:03, 10 September 2010 (UTC)

Hmm it didn't take that long.. btw I've already done it but I haven't uploaded it yet but I'll do so now... hmm by the way should the heading "risks" be separate from the "current assosciated research" heading?--[[User:Z3224500|Jenny Huang]] 02:53, 10 September 2010 (UTC)

Hey! Did it take long to do the drawing for the transabdominal technique? i was thinking we could do a second one the same for transcervical. what do you think? - Jill --[[User:Z3265772|z3265772]] 02:09, 10 September 2010 (UTC)

Im pretty sure its due monday for peer assessment, thats what it says in the course guide. did he say it was due thurs in the lab last week? hope its due thurs! that would be awesome! - Jill --[[User:Z3265772|z3265772]] 12:00, 9 September 2010 (UTC)

Hey Jill, wow only 4 days! I was mistaken that it was due next thursday. But don't wrry, I'll have the whole weekend to finish up ;)--[[User:Z3224500|Jenny Huang]] 08:30, 9 September 2010 (UTC)

Hi! Ive used a reference that is not from pub med, so you can copy that to use references that arent in pub med. :) only 4 days till its due! - Jill --[[User:Z3265772|z3265772]] 01:29, 9 September 2010 (UTC)

some pictures we can use, this first one is Primary chorionic villi, the second picture is secondary chorionic villi, these may be helpful when describing the technique -Jill --[[User:Z3265772|z3265772]] 09:52, 7 September 2010 (UTC)

[[File:Gray36.png|left|400 px]]

[[File:Gray37.png|left|400 px]]

Hmm so basically we do the peer review the week after mid sem break until the 23rd of september, and we paste both the review on the groups page and on your own page... also apparently the other student discontinued the course so its just us doing the project now =S --[[User:Z3224500|Jenny Huang]] 03:02, 2 September 2010 (UTC)

Yay!! looks awesome!! Sorry i couldnt be there today, could you let me know what Mark says? thanks :) - Jill --[[User:Z3265772|z3265772]] 23:59, 1 September 2010 (UTC)

I've uploaded the first pic... I hope it's ok and if I did the layers wrongly please tell me so I can edit... also how do you do referencing that is not from pubmed journals?--[[User:Z3224500|Jenny]] 23:18, 1 September 2010 (UTC)

Hi Jenny, are you doing the drawn figure still? would you possibly be able to upload it before thursday? i have updated references for my section :) - Jill --[[User:Z3265772|z3265772]] 08:52, 1 September 2010 (UTC)

--[[User:S8600021|Mark Hill]] 00:49, 31 August 2010 (UTC) I have emailed your missing team member , but have not had a response yet. Your should continue to work on the project together as best you can. It seems to be progressing, though I did ask you to update your reference format and I do not see a student drawn figure. You need to have this updated before this weeks lab when I will be reviewing all projects.

Hi Jill, I'm working on it :) by the way have you heard from the other team member? Oh and I'll be drawing pictures for both the transcervical and transabdominal techniques..--[[User:Z3224500|Jenny Huang]] 07:46, 30 August 2010 (UTC)

Hi guys, only two weeks to go, we really need to do some more work, the editing at the end will be the hardest, so the sooner we finish, the easier it will be. - Jill--[[User:Z3265772|z3265772]] 23:46, 29 August 2010 (UTC)

Can we incorporate some sort of timeline? what do you think? maybe we can do a timeline of embryo development and note the time that CVS is done - Jill --[[User:Z3265772|z3265772]] 00:57, 26 August 2010 (UTC)

Mark has kindly shown us how to reference, ill try to sort that out tonight or tomorrow - Jill --[[User:Z3265772|z3265772]] 23:16, 25 August 2010 (UTC)

Ive just discovered, you can use almost any picture on wiki, the copyrights have usually expired, which is why wiki can use them, just search CVS on wiki and if there is a picture you like, check the copyright and copy away!! :D -Jill --[[User:Z3265772|z3265772]] 01:05, 25 August 2010 (UTC)

Hi guys, please feel free to edit any work i have done, or add to it, or even suggest to me on this page what to add. what i have put up so far really is a rough draft and will be trying to add to it later anyway :) -Jill --[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

{{Template:Projects10MHtalk}}

Hi guys, we need to get on top of this, its due for peer assessment in 3 weeks! Im going to do related research. does anyone want to do the drawing? ill also try and get some more references and photos up, as Mark has suggested. If you want a picture, just email the website with the picture on it, thats what ive been doing, they are usually pretty good about it. let me know of any other ideas you guys might have - Jill --[[User:Z3265772|z3265772]] 09:50, 23 August 2010 (UTC)

--[[User:S8600021|Mark Hill]] 04:35, 23 August 2010 (UTC) OK there are a few references here, but you will need more than these few and there should be some related images.

Link for group assessment criteria: [[2010_Lab_1#Group_Assessment_Criteria|group assessment criteria]] - Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

For current associated research:

http://onlinelibrary.wiley.com/doi/10.1002/pd.2410/abstract

http://www.ncbi.nlm.nih.gov/pubmed/11263542

http://www.ncbi.nlm.nih.gov/pubmed/19683693

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T7V-4BWVXPY-F9&_user=10&_coverDate=03%2F31%2F1994&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1427646674&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a3c3f2d47ad01c562a3baea8c60a48bc

http://www.informaworld.com/smpp/content~db=all~content=a913951525

http://www.escardiocontent.org/periodicals/ejcpr/article/S0002-9378%2807%2900305-5/abstract

http://humrep.oxfordjournals.org/cgi/content/abstract/3/6/811

- Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

Hi guys, i put up the link for Search Pubmed for our topic, did we want to assign ourselves a role to do or just see how the page goes? i thought maybe we could find a page that we like and follow a similar format, that way we know what our page will look like and can follow a layout as we go. -Jill --[[User:Z3265772|z3265772]] 01:12, 9 August 2010 (UTC)

also, see this web page http://www.cdc.gov/mmwr/preview/mmwrhtml/00038393.htm Jill --[[User:Z3265772|z3265772]] 11:16, 9 August 2010 (UTC)

project outline:

1. Intro

2. historic background

3. current associated research

4. simplified description of technique

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

5. student drawn figure or animation

6. reference list

7. glossary

8. external links

-Jill --[[User:Z3265772|z3265772]] 03:05, 11 August 2010 (UTC)

Can anyone tell me how to paste a picture from an outside source? i cant seem to figure it out. thanks :)
-Jill --[[User:Z3265772|z3265772]] 05:03, 11 August 2010 (UTC)

dont worry, i figured it out :)

i think we should put the references list on this page to begin with to make sure we dont double up
- Jill --[[User:Z3265772|z3265772]] 05:31, 11 August 2010 (UTC)

Hey guys sorry for the delay in replies. I see you have made a contribution to the topic already :) By the way, where did you find the project outline criteria? Oh and if you don't mind I can do research on the description of technique and current research. Feel free to contribute :) oh and any ideas on how to work on the drawings? --[[User:Z3224500|Jenny Huang]] 15:29, 11 August 2010 (UTC)

Hello guys,

So I found some journal articles that is of interest especially this one: http://apps.who.int/rhl/reviews/langs/CD003252.pdf which is long and has extensive information on the topic..
So I'll be editing my section in word and will be posting some info on technique in the future.

Btw here are some other articles that are of interest that can be accessed through unsw sirius:

http://linkinghub.elsevier.com/retrieve/pii/S0889854505702916

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

http://journals.lww.com/co-obgyn/Abstract/2005/04000/Chorionic_villus_sampling_and_amniocentesis.16.aspx

Complications:

http://journals.lww.com/greenjournal/Abstract/2007/09000/Procedure_Related_Complications_of_Amniocentesis.24.aspx

http://journals.lww.com/greenjournal/Abstract/2008/10000/Evaluating_the_Rate_and_Risk_Factors_for_Fetal.12.aspx

I'll be adding more once I find some that are useful..

Oh and about the topic headings are we just going to use the ones in the assesment criteria?

--[[User:Z3224500|z3224500]] 15:03, 24 August 2010 (UTC)

Hey Jenny!! i think its a great idea to use more headings, add as many as you like/can think of, i just cant think of any more. i think the assessment criteria is just the bare minimum we have to do, so please add more! Also, can we add the new discussion posts to the top of the page? so we dont have to scroll to the bottom every time? what do you think? (it says up the top of this page to add newer material at the top, just wondering what you thought). i really like the articles you have found too :) see you tomorrow
- Jill --[[User:Z3265772|z3265772]] 00:29, 25 August 2010 (UTC)

2010 Group Project 2

2010-09-29T01:40:57Z

Z3224500: /* Hypertensive disorders of pregnancy */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Hypertension, or high blood pressure, is a condition where systemic arterial blood presssure is elevated. Hypertension is one of the most common medical problem during pregnancy, affecting about 2-3% of pregnancies.<ref>Gibson, P., Carson, M.P, 2010. Hypertension and Pregnancy. Accessed 29 September, 2010. <http://emedicine.medscape.com/article/261435-overview></ref>
Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

2010 Group Project 2

2010-09-26T22:59:41Z

Z3224500: /* Results and Accuracy */

[[File:Embryo_11-14_weeks.jpg|right|400 px]]

='''Chorionic Villus Sampling (CVS)'''=

=Introduction=

[[Image:Gray31.png|thumb|350px|right|Grays]]

Chorionic villus sampling or CVS is a type of prenatal diagnosis test performed in the first trimester to detect major fetal abnormalities such as down syndrome, cystic fibrosis and tay-sachs disease, among many others. In the procedure, tissue is withdrawn from small finger like projections on the placenta called chorionic villi and tested for chromosomal defects. It is commonly performed between 10 and 12 weeks of pregnancy.
The advantage of CVS over other procedures is that the result is available approx 6 weeks earlier in the pregnancy, so if a termination is needed, it can be done earlier which is much safer, rather than later in the pregnancy, which can carry more risks. <ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617.</ref>

''Reasons for getting chorionic villus sampling can include:''

-History of genetic disorders in the family

-Parents have already had a child with a disorder such as down syndrome or cystic fibrosis

-Abnormal ultrasound result

-Maternal age of 35 or older, which increases the risk of chromosomal defects such as down syndrome

=Historic background=

'''Brief timeline of CVS use'''

*1968 - Mohr in Scandinavia introduced the concept of prenatal diagnosis using chorionic villi sampling <ref><pubmed>5691288</pubmed></ref>
*1973 - Kullander and Sandahl and Hahnemann in 1974 showed further study into chromosomal analysis from CVS <ref><pubmed>4766093</pubmed></ref>
*1975 - from the Department of Obstetrics and Gynaecology at the Tietung Hospital in Anshan, China was successful in using CVS to determine sex of fetuses for sex pre selection. <ref><pubmed>811431</pubmed></ref>
*1980 - Kazy et al. were the first to use ultrasound guidance during chorionic villi sampling. <ref><pubmed>7208019</pubmed></ref>
*1981 - Niazi et al. improved methods for culturing of fibroblasts from trophoblast villi. <ref><pubmed>7208019</pubmed></ref>
*1983 - Ward performed transcervical CVS with 67% success rate. In the same year, the Brombati group demonstrated and 96% success rate with obtaining villi with the aid of ultrasound guidance <ref><pubmed>6463023</pubmed></ref>
*1984 - Smidt-Jensen and Hahnemann introduced transabdominal CVS under ultrasound guidance <ref><pubmed>4088973</pubmed></ref>
*1986 - The Golbus group had a 3.8% miscarriage rate, and subsequently many other clinics started reporting a much lower rate of miscarriage at 1.7% making the procedure safe for routine use <ref><pubmed>3717235</pubmed></ref>

===Jan Mohr (1921-2009)===
[[Image:Jan_Mohr.jpg|thumb|200px|left|Jan Mohr]]

'''1968 -- Concept of CVS introduced'''

In 1968 Jan Mohr introduced the concept of prenatal diagnosis using the CVS technique. <ref><pubmed>5691288</pubmed></ref> He used the transcervical method to get a biopsy of the chorion using an endoscope as the source of vision. The current technique differs by using mostly transabdominal access with ultrasound instead of an endoscope. He reported a 96% success rate in obtaining chorionic material but with a high incidence of bleeding and infection. The approach was abandoned as amniocentesis became more popular due to higher safety levels

'''1973-1975 -- Further study into chromosomal analysis from CVS'''

Kullander and Sandahl in 1973 and Hahnemann in 1974 further researched fetal chromosome analysis using transcervical biopsy before termination in early pregnancies. <ref><pubmed>4766093</pubmed></ref> In 1975 the first successful diagnostic use of chorionic villi was reported at the Tietung Hospital in China. <ref><pubmed>811431</pubmed></ref> This is where fetal sex was diagnosed for the purpose of sex pre-selection. They claimed to have 94% diagnosis success and only 4% miscarriage rate. Researchers in the United States were, however unable to duplicate the results and so the idea of CVS diagnosis was again abandoned for some time.

'''1980-1983 -- Change from endoscopic examination to ultrasound to guide CVS'''

With the invention of the ultrasound and advancement in molecular genetics, an earlier prenatal diagnosis was now sought after. So Kazy et al. in 1980, began using both the endoscope and the ultrasound for fetal sexing on chorion biopsies. This was the first report of using ultrasound guidance during chorion sampling. After Kazy et.al. began using the ultrasound for guidance, many others followed. Niazi et al., Ward and the Brombati group all started using ultrasound guided CVS. Techniques quickly improved and success rate of obtaining chorionic material rose from 75% to 96% <ref><pubmed>7208019</pubmed></ref>

'''1984-1986 -- The introduction of transabdominal CVS'''

In 1984, Smidt-Jensen and Hahnemann in Copenhagen introduced transabdominal CVS using ultrasound guidance. <ref><pubmed>6463023</pubmed></ref> With less chance of infective complications the procedure has become more popular than the transcervical method in many prenatal diagnostic centers. Other ultrasonic techniques and modifications were explored by the Brambati and Simoni group and the Golbus group in 1985. <ref><pubmed>4088973</pubmed></ref> The Golbus group reported in 1986 a miscarriage rate of 3.8%. <ref><pubmed>3717235</pubmed></ref> Subsequently, many other centres reported a much lower miscarriage rate of 1.5% which made the procedure safe for routine use.

==Table Comparing Prenatal Diagnosis Techniques==

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows invasiveness and timeframe for some prenatal diagnostic techniques
! Invasiveness !! Diagnostic technique !! Comments !! Time that procedure can be performed !! Diagram
|-
|Non Invasive
|[[2010_Group_Project_1|Ultrasound]]
|'''Tests for:''' neural tube defects, chromosomal abnormalities and congenital heart abnormalities

'''Risks:''' No risks currently indicated for ultrasound use in prenatal diagnosis.

This test uses high frequency sound waves through a transmitting device, which construct a picture of the fetus when the waves are reflected and received back by the transmitter. Due to no known risks, ultrasound use is used routinely in pregnancies and is the first port of call for prenatal diagnosis. If a potential abnormality is found or the parents are high risk, then a more invasive diagnostic technique may be recommended. The type of diagnostic technique used depends on the potential abnormality found. <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref>[[2010_Group_Project_1|More about Ultrasound]]
|Weeks 18-20
|[[File:ZConvex_Array_Transducer.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_2|Chorionic Villus Sampling]]
|'''Tests for:''' chromosomal abnormalities and genetic abnormalities

'''Risks:''' Miscarriage (1%), some of the side effects include dizziness, abdominal discomfort, cramping, haemorrhage, infection, ruptured amniotic sac, increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier <ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

With the guidance of Ultrasound, a needle is inserted in to the abdomen or through the cervix and a small sample of chorionic villi from the placenta are obtained. This sample is sent to a cytogenetics laboratory where the cells are cultured and stained, and photographed to view chromosomes
|Weeks 10-12
|[[File:Transabdominal_CVS.jpg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_3|Amniocentesis ]]
|'''Tests for:''' chromosomal abnormalities, fetal infections, and genetic abnormalities

'''Risks:''' Miscarriage <1%, stillbirths 3%, and small risk of infection. <ref><pubmed>PMC2464303</pubmed></ref>

A needle is inserted in to the uterus where a sample of the amniotic fluid surrounding the fetus is taken. This procedure is usually done with the guidance of ultrasound so the physician can see where the needle is being inserted. The amniotic fluid is analysed for abnormalities. [[2010_Group_Project_3|More about Amniocentesis ]]
|Weeks 15-16
|[[File:Process_of_amniocentesis.jpeg|right|150 px]]
|-
|Invasive
|[[2010_Group_Project_4|Percutaneous Umbilical Cord Blood Sampling]]
|'''Tests for:'''chromosomal abnormalities, blood disorders, some metabolic disorders, fetal infections, and some causes of structural problems.

'''Risks:'''Miscarriage <2%, Preterm labour, fetal bradycardia, bleeding of the umbilical cord. <ref><pubmed>16530195</pubmed></ref>

A small needle is inserted in to the abdomen of the mother and a sample of blood is taken from the umbilical vein in the umbilical cord. This technique is often used when other diagnostic techniques are inconclusive, but should be used with caution as carries higher risk rates. The benefit of Percutaneous Umbilical Cord Blood Sampling is that the results are available much faster, within 72 hours of testing. CVS and amniocentesis tests need culturing and therefore take up to 11 days for a result. [[2010_Group_Project_4|More about Percutaneous Umbilical Cord Blood Sampling]]
|Weeks 18-22
|[[File:Placenta_Anterior.jpg|right|150 px]]
|-
|Less Invasive
|[[2010_Group_Project_5|Fetal Fibronectin]]
|'''Tests for:'''determines the likelihood of premature birth in women of high risk

'''Risks:'''No known risks for the testing of Fetal Fibronectin, as is it less invasive than other techniques.

Fetal Fibronectin is only found in the uterus until the onset of labour when is secretes in through the cervix. In this procedure, a sample of the cervico-vaginal secretions are taken and sent to the lab for testing. If the test comes out positive for Fetal Fibronectin in the vagina, the mother has a chance of going into premature labour. [[2010_Group_Project_5|More about Fetal Fibronectin]]
|Weeks 24-34
|
|-
|Non Invasive
|[[2010_Group_Project_6|Maternal serum alpha-fetoprotein]]
|'''Tests for:'''AFP is a type of screening test and do not diagnose problems, but signal whether further testing is needed. Normal AFP levels are increased in Neural Tube Defects and Omphalocoele & decreased in Down Syndrome.

'''Risks:'''No known risks as Maternal serum alpha-fetoprotein is non invasive

A blood sample is taken from the mother and alpha-fetoprotein levels are measured in the lab. These measurements can determine the risk level of certain abnormalities in the fetus. The advantage is that it is non invasive, but the disadvantage is that it has a very high false positive rate, so many mothers have gone on to have amniocentesis or chorionic villus sampling to find nothing is wrong with the baby. This can be overcome by having another alpha-fetoprotein test before getting amniocentesis or chorionic villus sampling. [[2010_Group_Project_6|More about Maternal serum alpha-fetoprotein]]
|Weeks 15-20
|[[File:Enzyme_immunoassay.jpg|right|150 px]]
|-
|}

=Description of technique=

[[File:transabdominal_CVS.jpg|right|thumb|280px|Transabdominal Technique]]
[[File:transcervicalCVS.jpg|right|thumb|280px|Transcervical Technique]]

CVS can be performed in two ways, through the cervix (transcervical) or through the abdomen (transabdominal). Both techniques are equally safe when performed by an experienced technician, however miscarriage rates are somewhat higher when done through the cervix. Prior to the procedure, an abdominal ultrasound can be performed to locate the position of the uterus, and the placenta. A full bladder is not required. Depending on the type of method performed, the vulva, vagina, cervix or abdomen are cleaned with antiseptic. The procedure normally takes only 1-2 minutes to perform and the patient is able to leave the clinic within the hour after the fetus is checked.<ref>Melbourne Ultrasound for Women. Chorionic Villus Sampling. Accessed 5 September 2010. http://www.nevdgp.org.au/info/melb_us/cvs_melb.htm</ref>

===Transabdominal Procedure===

# A local anaesthetic is first applied to the abdomen. 
# A thin hollow needle is then inserted through the abdomen into the uterus and into the edge of the placenta where the chorion is located. An ultrasound transducer is commonly used to guide the needle during the procedure. 
# A finer syringe needle is then passed through the outer needle, and the tissue is then drawn. 
# The sample is taken to the laboratory for testing.

===Transcervical Procedure===
# A speculum is inserted in the vagina and the area is cleaned with antiseptic. 
# With the help of ultrasound imaging, a thin cannula is then inserted through the cervix and uterus and into the placenta. 
#The tissue sample is then taken up through the cannula. 
<ref><pubmed>20154617</pubmed></ref>

After the sample is taken to the laboratory, the cells are grown until there are enough cells for chromosome testing. The results normally take up to 2 weeks to complete.

===Complications===

Some of the side effects and complications after a CVS procedure can include:

* Dizziness
* Abdominal discomfort
* Cramping
* Haemorrhage
* Infection
* Ruptured amniotic sac
* Increased risk of limb defects if the test was performed at nine weeks’ gestation or earlier
* Premature delivery
<ref>Alfirevic, Z., K. Sundberg, et al. 2008. "Amniocentesis and chorionic villus sampling for prenatal diagnosis (Review)." Cochrane Database of Systematic Reviews 4: 1-134.</ref>

Additional complications can involve technical errors such as failure of the specimen to grow sufficiently in the laboratory and uncertain laboratory results. If this occurs, amniocentesis is still an option after 15 weeks.

===Results and Accuracy===

The accuracy of CVS to detect chromosome abnormalities is quite high, at around 98-99% <ref>Hall, Judith G. "Chromosomal Clinical Abnormalities." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.</ref>. Although it has a high accuracy rate to diagnose most major chromosomal problems, CVS does have some limitations. Having a negative result for an abnormality does not rule out ALL genetic defects the baby may have. Comparatively to amniocentesis, CVS does NOT detect neural tube defects such as spina bifida, or anencephaly.
The type of chromosome abnormalities detected by CVS will be further discussed in detail below.

===Limitations===
[[file:Double_tetrasomy_18_mosaicism.jpg‎|thumb|250 px|Example of a child with double tetrasomy 18+ mosaicism.]]

'''Maternal contamination'''

Since the villus sample also involves maternal cells, there is a possibility that they may take over the laboratory culture instead, consequently leading to the mother's cells being tested instead of the fetus's cells. The risk of this happening is low however and is decreased when the sample contains an adequate amount of fetal cells.

'''Mosaicism'''

"Mosaicism" occurs when both abnormal and normal cells are found in the chorionic villi. Mosaicism can involve both the fetus (true fetal mosaicism) and the placental tissues or the placental tissues alone. When this happens, cells that multiply from these abnormal cells may develop a chromosome anomaly.
What can result is that in certain body organs the fetus has a combination of cells that are abnormal and normal in genetic structure.
The rate of the placental type occuring is found in 1-2% of pregnancies detected by CVS.<ref><pubmed>9316125</pubmed></ref> When mosaicism is detected by CVS, the limitation lies in the inability to conclude that the baby itself and not just the placental tissues will share the mosaicism. Even if the baby is affected, it will be unclear as to what percentage of the fetal cells and the type of organs that will be affected.<ref>Trofatter. K.F. 2008. Chromosomal Mosaicism Detected at the Time of Chorionic Villus Sampling. Accessed on 15 September 2010. http://www.healthline.com/blogs/pregnancy_childbirth/2008/03/chromosomal-mosaicism-detected-at-time.html</ref>

=Risks=

When Chorionic Villus Sampling is performed, a small sample of the placenta is removed for analysis. The placenta contains fetal material, therefore can reveal genetic defects which may lead to problems or abnormalities. <ref><pubmed>20664398</pubmed></ref> This prenatal test can be performed as early as 11 weeks into the pregnancy, this is earlier than many prenatal diagnosis tests, which is why many parents choose CVS as they can have solid information earlier in the pregnancy. Some common risks which are not under current research include: Cramping, light blood spotting, pain, fever and chills, leakage (which can be a major concern as it can lower amniotic fluid to a dangerous level for the infant), and potential for missing fingers and toes in the newborn. For this reason, the procedure is only recommended for women who are at least 11 weeks pregnant. <ref><pubmed>20051662</pubmed></ref> The other major risks that are currently being researched are outlined below

====Transabdominal vs Transcervical CVS. Comparison of risks====

[[File:CVS_Table.jpg|left|thumb|280px|Transabdominal vs Transcervical risks]]

This table shows the symptoms of women approximately 3 days after sampling. The table shows women who had undergone transcervical sampling had higher frequencies of fluid leakage, vaginal spotting, and bleeding. When a tenaculum is not used, the frequency of vaginal spotting and bleeding persisted in the transcervical-sampling group. Only two women, both in the transcervical-sampling group, had a temperature above 38°C. <ref>Jackson, L.G., Zachary, J.M., Fowler, S.E., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Mahoney, M.J., Pergament, E., Simpson, J.L., Black, S. & Wapner, R.J. 1992, "A Randomized Comparison of Transcervical and Transabdominal Chorionic-Villus Sampling", New England Journal of Medicine, vol. 327, no. 9, pp. 594-598.</ref>

====Miscarriage====

One of the biggest risks of Chorionic Villus Sampling is miscarriage. In one to 100 or 200 cases, the procedure is linked with miscarriage. <ref><pubmed>19155918</pubmed></ref> In an experienced clinic, this rate may go down to one in 300 to 400. To lower the risk of miscarriage with Chorionic Villus Sampling, it is recommended the procedure be performed by an experienced clinician

====Oligohydramnios====

Oligohydramnios is a condition due to low amniotic fluid level, which is caused by amniotic fluid leakage. Amniotic fluid leakage is typically caused by fetal urinary tract abnormalities such as Potter's syndrome, polycystic kidneys, or genitourinary obstruction. But leakage can sometimes be caused by sampling of the chorionic villi due to insertion of the needle. If the resulting oligohydramnios is not treated and the amniotic fluid continues to leak it can result in the baby developing hypoplastic lungs (underdeveloped lungs). <ref><pubmed>17694578</pubmed></ref> 

'''Why would you use CVS over other techniques?'''
{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ Advantages and Disadvantages of Chorionic Villus Sampling
! Advantages !! Disadvantages
|-
|Can be performed earlier in pregnancy than amniocentesis (at around ten weeks).

Results are available faster

Cells obtained are mitotically active

Amount of tissue obtained is preferable for DNA analysis.

It is almost 100% reliable in detecting chromosomal and genetic defects.
|It carries a slightly higher risk of miscarriage (1%-2%) than does amniocentesis

It's less commonly available than amniocentesis, and fewer doctors are experienced in the procedure.

It entails a greater risk of distorted results than does amniocentesis due to presence of mother's cells in the sample and discrepancies between chorionic villi and fetal genes.

Metabolic disorders are difficult to diagnose and must be confirmed with amniocentesis.

Because of the early gestational age at which the test is performed, fetal anatomy cannot be seen as well as it can at the time amniocentesis is performed.
|-
|}
<ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>

=Abnormalities found by CVS prenatal diagnostic technique=

[[File:Down-normal.gif|right|thumb|280px|Normal]]

[[File:Down-extra.gif|right|thumb|280px|third copy of chromosome 21]]

The cells collected by CVS are sent to a cytogenetics laboratory. There the cells are cultured (stimulated to grow and divide) for 10-14 days. After enough cells are obtained, a banded karyotype is performed. This means that the fetal chromosomes in the cultured cells are stained and subsequently photographed. The photographed chromosomes are then ordered by number, counted and checked for structural abnormalities. There should be 46 chromosomes, 23 pairs. A boy's karyotype is described as 46,XY and a girl's karyotype is described as 46,XX.<ref>Rhoads, G.G., Jackson, L.G., Schlesselman, S.E., de, l.C., Desnick, R.J., Golbus, M.S., Ledbetter, D.H., Lubs, H.A., Mahoney, M.J., Pergament, E., Simpson, J.L., Carpenter, R.J., Elias, S., Ginsberg, N.A., Goldberg, J.D., Hobbins, J.C., Lynch, L., Shiono, P.H., Wapner, R.J. & Zachary, J.M. 1989, "The Safety and Efficacy of Chorionic Villus Sampling for Early Prenatal Diagnosis of Cytogenetic Abnormalities", New England Journal of Medicine, vol. 320, no. 10, pp. 609-617. </ref>

{|border="1px" cellspacing="1" align="center" cellpadding="5"
|+ This table shows what disorders CVS detects, the cause, frequency and any comments
! Disorder !! Cause !! Comments !! Frequency !! Picture
|-
|[[ Trisomy 21 | Down Syndrome ]]
|A third copy of chromosome 21

Normally, there are only two copies of this chromosome
|The average IQ of children with Down syndrome is around 50, compared to normal children with an IQ of 100. Complications for people with down syndrome include: congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions. <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref> The picture shows a newborn infant with Down Syndrome (Trisome 21)
|Approximately 1 in 1,000 births <ref>Malone, F.D., Canick, J.A., Ball, R.H., Nyberg, D.A., Comstock, C.H., Bukowski, R., Berkowitz, R.L., Gross, S.J., Dugoff, L., Craigo, S.D., Timor-Tritsch, I., Carr, S.R., Wolfe, H.M., Dukes, K., Bianchi, D.W., Rudnicka, A.R., Hackshaw, A.K., Lambert-Messerlian, G., Wald, N.J. & D'Alton, M.E. 2005, "First-Trimester or Second-Trimester Screening, or Both, for Down's Syndrome", New England Journal of Medicine, vol. 353, no. 19, pp. 2001-2011. </ref>
|[[File:Trisomy_21_newborn.jpg|right|200 px]]
|-
|[[ Trisomy 13 | Trisomy 13 ]]
|A third copy of chromosome 13

Normally, there are only two copies of this chromosome
|Also called Patau syndrome. This abnormality causes mental and motor abnormalities, polydactyly (extra digits), kidney defects, abnormal genitalia and heart defects, among many others. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows an infant with polydactyly, a potential complication of Trisome 13
|Less than 1%
|[[File:220px-Patauhand.PNG|right|200 px]]
|-
|[[ Trisomy 18 | Trisomy 18 ]]
|A third copy of chromosome 18

Normally, there are only two copies of this chromosome
|Also known as Edwards syndrome. It has a very low survival rate, due to: kidney and heart defects, intestines protruding outside the body, mental abnormalities, growth disorders, feeding and breathing difficulties. <ref>Driscoll, D.A. & Gross, S. 2009, "Prenatal Screening for Aneuploidy", New England Journal of Medicine, vol. 360, no. 24, pp. 2556-2562. </ref> The picture shows a clenched hand and overlapping fingers: index finger overlaps third finger and fifth finger overlaps fourth finger, characteristically seen in Trisomy 18.
|1 in 3,000 conceptions and approximately 1 in 6,000 live births
|[[File:200px-Overlapping_fingers.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Cystic_fibrosis Cystic Fibrosis]
|A mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR) in chromosome 7.
|An autosomal recessive disease that causes excessive sticky mucous to form on mucosal surfaces effecting the digestive and respiratory organs. <ref>Levison, J.H., Barbieri, R.L., Katz, J.T. & Loscalzo, J. 2010, "Hard to Conceive", New England Journal of Medicine, vol. 363, no. 10, pp. 965-970. </ref> The picture shows clubbing of the fingers in a person with cystic fibrosis
|Approx 1 in 3,000
|[[File:220px-ClubbingCF.JPG|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Hemoglobinopathy Hemoglobinopathy]
|Structural abnormalities in the globin proteins
|Multiple types of abnormal haemoglobins exist including Haemoglobin S, C E and D that alter the structure of these proteins. A common defect is sickle cell disease.<ref>Abboud, M.R. 2009, "Hematopoietic Stem-Cell Transplantation for Adults with Sickle Cell Disease", New England Journal of Medicine, vol. 361, no. 24, pp. 2380-2381. </ref>
|Hemoglobinopathies are a genetic defect and therefore an inherited disorder, frequency depends on which particular hemoglobinopathy is being discussed, eg. in the case of Sickle cell disease, it is estimated that 7% of worlds population are carriers
|[[File:Series_10-09.jpg|right|200 px]]
|-
| [http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease Tay Sachs Disease]
|mutations on chromosome 15 in the HEXA gene
|It is a rare autosomal recessive defect inherited from parents that are carriers for the disease. Affected individuals suffer from premature nerve cells death in the brain. <ref><pubmed>20100466</pubmed></ref>
|Approx 1 in 300 are carriers
|[[File:220px-Autorecessive.svg.png|right|200 px]]
|-
|}

=Outcomes=

=Ethical concerns=

=Current associated research=

Chorionic Villus Sampling (CVS) is one of many prenatal diagnostic tools for expectant mothers, it is popular since it can be used to identify potential problems with a fetus at a very early stage. However, the procedure does carry some risks, as does any invasive diagnostic procedure. As chorionic villus sampling is a relatively new technique, made available for safe routine use only 20 years ago, the current associated research is mainly associated with risks associated with the procedure, and ways to overcome these risks. The next section in this page will discuss the current research on CVS and the risks involved in the procedure, and not what the test results may find.

====Hypertensive disorders of pregnancy====

Pregnancy induced hypertension is a condition that can occur during and after the 20th week of pregnancy. The types of hypertensive disorders can include:

[[File:Enamel_Hypoplasia_Due_to_Maternal_Toxemia.jpg|thumb|200px|right|Enamel hypoplasia due to maternal toxemia]]

*Pre-eclampsia or toxemia – Characterised as high blood pressure above 140/90 with proteinuria (protein in the urine that is above 300mg)
* Eclampsia - Developed in a pregnant woman who has had pre-eclampsia and is characterised by seizures
* Gestational hypertension – arterial hypertension that occurs after the 20th week of gestation

If untreated, the condition may develop into HELLP syndrome which is a serious complication noted by hemolytic aneamia, elevated liver enzymes and a low platelet count.

There has been conflicting evidence in literature that suggests that CVS is associated with hypertensive disorders in pregnancy such as pre-clampsia and gestational hypertension. In several studies, such as data from the National Institute of Health that compared late CVS procedures with early amniocentesis, showed a higher rite of gestational hypertension and preeclampsia in pregnant mothers.<ref><pubmed>15738029</pubmed></ref> (5.4% for mothers who had CVS and 3.5% that had amniocentesis.) It was hypothesized that disruption and disturbance of the placenta at 13-14 weeks may increase the risk of maternal hypertension. In addition, another recent study in 2006 also reported that there was an increase in the rate of pre-clampsia in first-time expectant mothers who have had CVS.<ref><pubmed>19455602</pubmed></ref>

However, in a very recent data investigation of among 9098 women that were pregnant between 1990 and 2006, the overall incidence of hypertensive disorders with women who have had CVS was 2.7% compared to the control group that did not have the procedure done which was 7.1%.<ref><pubmed>19918960</pubmed></ref> Similarly, in a study conducted by The American College of Obstetricians and Gynecologists,<ref><pubmed>20664398</pubmed></ref> 31, 138 women were that were included in the investigation showed that 2.2% developed preeclampsia and 2.8% developed gestation hypertension. Only 7.8% of those individuals had previously had CVS procedure performed.

Although it can be said that some woman may develop hypertensive disorders during pregnancy that have also had the CVS procedure done in the past, there is no conclusive evidence so far that definitively associates CVS with hypertensive disorders such as pre-clampsia and gestation hypertension.

====Malformations====
[[File:Craniosynostosis_.jpg|right|250 px]]

Many malformations were thought to be a result of more invasive prenatal diagnostic techniques such as chorionic villus sampling. These malformations include, but are not limited to, cardiac malformations, hypospadias, craniosynostosis, pyloric stenosis, inguinal hernia, polydactyly, syndactyly, hydrocephalus and cleft lip and palate. Although these studies have now confirmed no known relationship with CVS, we will mention some below. <ref><pubmed>7937577</pubmed></ref>

'''Craniosynostosis''' is a condition where one of the sutures of the skull prematurely fuses, this causes the other sutures to compensate in growth for the fused suture. In normal development of the skull, the sutures allow for brain growth, so if one suture fuses prematurely, the brain can not grow normally, and the other sutures over expand in compensation. In the shown image, pictures a1 and a2 show the normal development and fusing of the infant skull. b2 shows how a suture is prematurely fused and b1 shows how the abnormality shows in an infant child.
Craniosyntosis may result in increased pressure on the brain and developmental delays. Treatment of craniosynostosis usually consists of surgery to the skull where a zigzag incision is made to make the hair look more natural than the scar left by a straight incision. The surgery separates the sutures that have joined together to allow the head to develop normally.

<ref>Silver, R.K., Macgregor, S.N., Muhlbach, L.H., Knutel, T.A. & Kambich, M.P. 1994, "Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures", Prenatal diagnosis, vol. 14, no. 6, pp. 421-427. </ref>

[[File:Polydactyly.jpg|left|200 px]]
'''Polydactyly''' is a congenital condition where an extra digit is formed. Mostly it occurs on only one hand or foot, but sometimes can occur on all limbs. The extra digit is mostly a small non-function appendage of skin, less often it is an extension of the adjacent digit, and rarely it is a fully functioning finger that arises from the wrist or ankle joint like the other digits. Polydactyly can be described as:

● postaxial polydactyly (arising from the little finger)

● preaxial polydactyly (arising from the thumb) or

● central polydactyly (arising from anywhere between the other digits)

Polydactyly is seen in 1 in every 500 births, but the extra digit is usually surgically removed shortly after birth
<ref><pubmed>20661588</pubmed></ref>

[[File:Syndactyly2.JPG|left|200 px]]
'''Syndactyly''' is also a congenital condition, but is seen when digits are fused together. Syndactyly can be described as:

● simple syndactyly (where only skin is fused to the adjacent finger)

● complex syndactyly (where the bone is fused together)

● incomplete syndactyly (where fusion is only part of the way up the digit), and,

● complete syndactyly (where fusion is to the tip of the digit)

The picture on the left shows an example of polysyndactyly, where the digits are both fused, and there is an extra digit.
<ref><pubmed>20811188</pubmed></ref>

====Hemangiomas====

[[File:Capillary_haemangioma.jpg|thumb|200px|right|Hemangioma]]

A hemangioma is a benign tumour growth of endothelial cells that can occur in newborns and infants. Hemangiomas can occur anywhere in the body but are often localised on the skin of the face and neck, and are characterised by a red to reddish purple raised lesion on the skin, similarly to a "strawberry" like appearance. Its red appearance is due to the newly formed blood vessels, which result from the malformation of angioblastic tissues of fetal life.<ref><pubmed>7063565</pubmed></ref>
Most hemangiomas do not cause any serious complications, and regress later on in life, where 90% of hemangiomas in children would disappear by the age of 9.

Recently, research has linked the increase in the incidence of hemangiomas in infants following CVS. It has been postulated that the mechanism of hemangioma formation is associated with the embolisation of angioblasts or endothelial cells from the placenta to the fetal skin.<ref><pubmed>19218861</pubmed></ref> Although this may link hemangiomas to placental origin, it is unclear how, or whether CVS directly interferes or enhances the formation of these lesions. However, a recent study that compared the effects of CVS and amniocentesis on the prevalence of hemangiomas in infants showed that 27% of the study group had hemangiomas with CVS compared to 9.4% in children with hemangiomas and amniocentesis. <ref><pubmed>20824891</pubmed></ref> Furthermore, in an previous study conducted in 1995, there was a threefold increase in incidence after trancervical procedure was done, compared to amniocentesis.<ref>Lo, K., Mihm, M. & Fay, A. 2009, "Current Theories on the Pathogenesis of Infantile Hemangioma", Seminars in ophthalmology, vol. 24, no. 3, pp. 172-177. </ref><ref><pubmed>7784377</pubmed></ref>

=Future of Chorionic Villus Sampling=

=Useful links=

'''Search Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Search Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Chorionic%20villus%20sampling Chorionic villus sampling]

'''Wikipedia'''[http://en.wikipedia.org/wiki/Chorionic_villus_sampling Chorionic villus sampling]

'''Fact sheets''' [http://www.thewomens.org.au/ChorionicVillusSamplingCVS Chorionic villus sampling]

'''Images''' [http://www.google.com.au/images?q=chorionic+villus+sampling&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=yCWcTKT-NsircY-nzNEJ&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CD4QsAQwAw&biw=1280&bih=615 Chorionic villus sampling]

'''You tube video of procedure''' [http://www.youtube.com/watch?v=0XUZsvTkEnw Chorionic villus sampling]

=Glossary=

'''Amniocentesis''' - A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.

'''Amnion''' - An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus.

'''Amniotic cavity''' - The fluid-filled (amniotic fluid) extraembryonic coelom (cavity) formed initially by epiblast and then ectoderm and surrounding extraembryonic mesoderm. In humans, it forms the innermost fetal membrane, produces amniotic fluid expanding to fuse with the chorionic membrane during week 8 of development.

'''Amniotic fluid''' - The fluid that fills amniotic cavity totally encloses and cushions the embryo.

'''Cannula''' - A flexible medical tube with a sharp-pointed part at one end that is inserted into a duct, vein, or cavity in order to drain away fluid or to administer drugs

'''Chorion''' - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.

'''Chorionic villus sampling (CVS)''' - The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.

'''Chromosome''' - double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

'''Ectoderm''' - One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo.

'''Endoscope''' - a long slender medical instrument for examining the interior of a bodily organ or performing minor surgery

'''Endoderm''' - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.

'''Fetus''' - In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

'''Gene''' - A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.

'''Gestation''' - The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

'''Mesoderm''' - The middle layer of the 3 germ cell layers of the trilaminar embryo.

'''Miscarriage''' - A general clinical term for the loss of embryo or fetus by spontaneous abortion.

'''Mitosis''' - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid).

'''Prenatal diagnosis''' - any of the diagnostic procedures used to determine whether a fetus has a genetic abnormality

'''Tenaculum''' - instrument used to grasp the cervix and keep the uterus in place during gynecological procedures.

'''Termination''' - The spontaneous or artificially induced expulsion of an embryo or fetus. As used in legal context, the term usually refers to induced abortion.

'''Transabdominal''' - In the transabdominal CVS technique, the physician inserts a needle through the abdomen into the placenta. This is also done with ultrasound, to guide the physician

'''Transcervical''' - In the transcervical CVS technique, the physician inserts a small tube through the cervix into the placenta. This is done while ultrasound guides the physician

'''Ultrasound''' - A non-invasive technique for visualizing and prenatal diagnosis of several features of development including: follicles in the ovaries, the gestational sac, fetus in the uterus, fetal parameters, and the placenta. The technique uses high-frequency sound waves that are reflected off internal structures. These reflections can then be analysed and displayed by computer.

'''Villi''' - Plural of villus, which is a thin projection from a surface. A term used to describe the many functional units together of the fetal placenta.

'''Vitelline arteries and veins''' - The blood vessels which form in the extraembryonic mesoderm of the yolk sac and anastomose are called vitelline arteries (flow away from the embryo) and vitelline veins (flow toward the embryo).

==Prenatal Diagnosis Terms==

'''false negative rate''' - The proportion of pregnancies that will test negative given that the congenital anomaly is present.

'''false positive rate''' - The proportion of pregnancies that will test positive given that the congenital anomaly is absent.

'''negative predictive value''' - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.

'''positive predictive value''' - The probability that a congenital anomaly is present given that the prenatal screening test is positive.

'''pre-implantation genetic diagnosis''' - (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.

'''prenatal screening sensitivity''' - (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.

'''prenatal screening specificity''' - The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.

==Glossary Links==

:[[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]

=References=
<references/>

== 2010 ANAT2341 Group Projects ==

[[2010_Group_Project_1|Project 1 - Ultrasound]] | [[2010_Group_Project_2|Project 2 - Chorionic villus sampling]] | [[2010_Group_Project_3|Project 3 - Amniocentesis]] | [[2010_Group_Project_4|Group Project 4 - Percutaneous Umbilical Cord Blood Sampling]] | [[2010_Group_Project_5|Project 5 - Fetal Fibronectin]] | [[2010_Group_Project_6|Project 6 - Maternal serum alpha-fetoprotein]] | [[ANAT2341_2010_Students|Students Page]]

{{Template:Footer}}
[[Category:2010ANAT2341]] [[Category:Science-Undergraduate]]

Talk:2010 Group Project 2

2010-09-26T22:57:28Z

Z3224500:

Umm.. I'm not sure about that, because the sources I found mosaicism on had it in their "limitations" heading... --[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)--[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)

Hey Jenny, do you think Mosaicism should be in the abnormalities found by CVS section? a few people have commented that its a bit confusing what the test detects and the risks associated with testing. i think Mosaicism is more under the heading of what cvs detects --[[User:Z3265772|z3265772]] 04:16, 23 September 2010 (UTC)

hey jill,
group 6 here, you may use our picture

--[[User:Z3254433|z3254433]] 09:07, 26 September 2010 (UTC)

===to fix===

'''Begin''' by collating the comments.
* What are the common criticisms?
* What were the best aspects identified within your project?
* What errors, typos, missing references were identified?
* Were there contributions from individual group members that were identified as good or poor parts of the overall project?

'''Then''' work on the changes.
* Develop priorities.
* Divide the changes and corrections between group members.
* Are there additional changes that should be made that were not identified by peer assessment.

'''Jill:'''

abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? comparative genomics, Improvements?

future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether

DONE move glossary above references so you dont have to scroll all the way down to read them

DONE table comparing other techniques

DONE got confused between the risks of this test and what it predicted (this will be clear in the above table)

DONE -it didn't state that the test was invasive in intro (table)

DONE -All spelling amd grammar - some more editing of spelling is required

DONE "abnormalities found by CVS" section towards the top of the page coz I got confused between the risks of this test and what it predicted

DONE -link or a reference to the brief time line where you state the names of the authors

DONE -The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed

DONE -I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources

DONE -a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work

DONE - it would be that you put the advantages/disadvantages of CVS over other techniques in a table.

'''Jenny:'''

flowchart or more pictures of procedure

clarify what hypertension is in the hypertensive disorders of pregnancy section

possibly more pictures or a flowchart of the procedure itself?

outcomes + ethics,

DONE Are the transabdominal and the transcervical pictures the student-drawn ones? put up in discussion that you drew them and you give permission for re-use - Jenny, ive done this for you, all you need to do is edit and add your student number, -Jill

elaborate on procedure eg what cells are being taken etc and stages of chorionic villus in embryology

DONE Spelling and grammar, - Jenny, ive gone through the page and edited the spelling mistakes i could find, could you please do the same incase ive missed any? and double check the sections you are about to write? Thanks :) - Jill --[[User:Z3265772|z3265772]] 00:33, 24 September 2010 (UTC)

The current research section could be put more into point form to make it more inviting to read - not sure if you want to do this, i think its ok as it is, maybe just delete this suggestion? or add pictures of people researching? haha

----

==Peer Review==

'''Please note!''' when posting your peer review, we only have two group members. the other one dropped out. Thanks :)

--[[User:Z3129413]] 16:29, 22 September 2010 (UTC)
I love those old timey pencil medical pictures and so for me this was really great, what instantly nailed the whole positive immediate impression was 'Reasons for getting chorionic villus sampling etc etc' right there at the beginning. Why would I get one? thanks very much. Perhaps a darker font would make it even better. Historical back ground is really good and technique pictures are of high standard. The table presentation of abnormalities found and ratios is such an effective way of portraying this information.

A few Q's with the hypertension cvs topic,
Is there a normally expected percent of women in a large population to develop hypertensive disorders, just for perspective? CVS would not lower incidences of such surely (9098 pop, 2.7% to 7.1% control). 138 study size seems a bit low, is result really much more significant? However I did understand that CVS was more risk prone than amniocentesis for pre eclampsia and gestational hypertension.
This project is well on track.

Group 2: Your project is very impressive in content as well as organisation. The most notable thing for me was the wide use of pictures which must have taken a lot of time and effort to source. They definitely create an engaging page especially in conjunction with the use of tables and clear subheadings. The structure you have used is very effective as it allows your information to be scientific and thorough but at the same time it is concise and easy to navigate. I felt like i got an extensive overview of CVS after having read your page and the use of pictures and subheadings kept it from being a chore. I felt the history and abnormalities sections were particularly interesting. I also appreciate how you have seemed to approach this topic from all angles and not just a one-sided, all current and positive viewpoint. To improve your page perhaps you could explore the future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether. Either way your page is probably up to standard as it is and it is obvious that you have worked hard at it. Job well done.
--[[User:Z3293029|z3293029]] 14:38, 22 September 2010 (UTC)

Group 2: fantastic use of images, it definitely worked to your advantage in engaging your audience's attention. Over all the language used is relatively easy to follow yet informative. As someone has already mentioned, some more editing of spelling is required. The amount of attention to detail is evident in the references which are from a range of sources so well done. I particularly liked that the page covered accuracy and limitations of the diagnostic procedure. Something that lacked clarity in a few other groups. Good use of the table covering the abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? Improvements?
Just an idea. Well done overall. --z3241780 13:40, 22 September 2010 (UTC)

'''GROUP 2: Chorionic Villi Sampling'''

This page caught my attention as soon as I saw it and that made me want to read on and thus learn about Chorionic Villi Sampling. A lot of research has gone into this assignment and it’s evident in the information presented as its precise which also helps capture the readers. The amount of research is also evident in the long list of references. The webpage is actually extremely informative covering pretty much every aspect of the pre-natal diagnostic techniques. Your webpage has the most pictures and this helps it stand out as one of the best project pages. I really, really like the formatting and the tables. The images break up the information so you’re never overloaded with the amount of text. The only bit of criticism is spelling but this is extremely minor as you’ll pick up on the spelling mistakes when you go over the page. The language in is the right mixture of scientific language meaning that even people without a scientific background can understand the CVS. Great job guys you really can’t tell that only two people are in this group. It’s extremely good!!! I also really like the first picture you have, gives a page a really good feel to it.

--[[User:Z3252635|z3252635]] 13:20, 22 September 2010 (UTC)

Hi guys!

You have found so many great pictures! Your page looks amazing. I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources. Your timeline was great too; I really like how you put up the concise timeline and then expanded a bit on the major developments afterwards. Are the transabdominal and the transcervical pictures the student-drawn ones? If so, well done! They’re really clear and beautifully done, but you should probably label them as student drawn and put in the copyright statement. If I could suggest something, it would be that you put the advantages/disadvantages of CVS over other techniques in a table. Otherwise, your page is really easy to read, and again has brilliant visuals – great job!--[[User:Z3252833|z3252833]] 12:42, 22 September 2010 (UTC)

CVS.

Group 2, your project is looking great, the first thing i noticed when reading it is that there is lots of detail which shows a great depth of research has gone into it, which is supported by your reference list. Another thing is the amount of pictures which support the information and break it up to make it easier to take in so much information at once. The disorders table provides great detail and makes it interesting with the pictures.

What could be improved: You could put the advantages/disadvantages into a table form to make it even easier to understand. The reasons to use this technique could be slotted into the procedure section instead of the introduction maybe as it shows who is eligible for the procedure. The current research section could be put more into point form to make it more inviting to read. But overall really great project.

--[[User:Z3292208|z3292208]] 08:55, 22 September 2010 (UTC)

This project is extremely well done. It seems a great effort has gone into proper referencing which also gives the impression of a thoughtful attempt. The balance of information mediums is great and the logical flow of ideas when reading through each section is perfect.
Suggestion: possibly more pictures or a flowchart of the procedure itself?

Well done :)

--[[User:Z3254753|z3254753]] 16:55, 21 September 2010 (UTC)

Group 2- This project had tons of photos which is super great because its much easier to follow... Most of the point made is supported with pictures ..definetly provided me a better understanding of CVS ..I agree with what others have mentioned its very informative and especially with just 2 team members .. fantastic work

what could be improved = a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work ..--[[User:Z3305561|Navneet Ahuja]] 12:53, 21 September 2010 (UTC)

Group project 2: chorionic villus sampling

This group had great images and the page layout was good too especially the tables which simplified the information and made it easier to read. The information presented was very informative, scientific, and all the key concepts were covered on the topic. The project had a very impressive reference list, and it did help in my understanding of this prenatal diagnostic technique.

What could be improved?
I did find a spelling mistake under the heading Results and Accuracy were you have written “maybe” instead of “baby”, so maybe proof read the assignment to pick up on any other possible spelling or grammatical errors, other than that well done.

--[[User:Z3254433|z3254433]] 07:15, 20 September 2010 (UTC)

This project was highly informative about CVS. It contained a lot of information in which it shows that a lot of research has gone into it. Everything has been covered like, what the test predicts and what risks are associated with this test. It was very scientific, yet easy to understand at a non-scientific level. I liked the external links how it directed me straight to a page of different articles about CVS.

What could be improved is maybe placing the "abnormalities found by CVS" section towards the top of the page, because i was a bit unsure on what this test predicted in the first place. I got confused between the risks of this test and what it predicted. But I managed to understand it all once all read through. Also, a definition of a "cannula" may be helpful in the glossary too, i wasn't sure what that exactly was.

--[[User:Z3291079|z3291079]] 02:48, 21 September 2010 (UTC)

This project provides a clear understanding of the key information regarding CVS, such as how it is carried out, the risks and benfits of CVS, what it is used for as well as future research. I have find the pictures to be of a great help in explaining the procedure of CVS.

One think I did notice was that, it didn't state that the test was invasive until you figure it out when you look at the pictures in the procedures. I think stating that in the introduction would make it clearer for readers to follow on with the information this projects provides having that knowledge in mind at the start.

--[[User:Z3216889|3216889]] 12:13, 22 September 2010 (UTC)

This web page is definitely one of my favorites. The information that you have provided is exceptional; the reference list is indicative of your extensive research. The table of deformities was a stand out for me as it was very well set out and was a effective break from the text. You also used excellent external links that were very well placed within the web page. A slight improvement would be to include a link or a reference to the brief time line where you state the names of the authors, and as previously mentioned, reference the statistics that you have included. Other than that, I applaud you for a job well done!--[[User:Z3252083|z3252083]] 12:22, 22 September 2010 (UTC)

--Group 2 Chronic villus sampling
This webpage shows that the group was very thorough in the research due to the amount of detail that has gone into it and its many links. The layout is very well set out which helps someone understand it if he/she has no previous knowledge of the concept. The use of pictures and diagrams were done well as it broke the page up making it very easy to read and take in the information. The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed. That’s all guys and well done considering you only had 2 people working on it.

--[[User:Z3290040|3290040]] 10:19, 22 September 2010 (UTC)

----

----

===group discussion===

I agree the page feels more "in order" now. yeh... its tough trying to find more information. I guess i'll expand on maybe on some of the abnormalities? I was thinking we can get pictures of the several diseases but it will probably be a little difficult due to copyright? hmm if i get new ideas from now until tommorrow i'll definately add more stuff in --[[User:Z3224500|Jenny Huang]] 06:38, 15 September 2010 (UTC)

Hey Jenny, i changed the order of the page around, i think it makes more sense now, before it didnt really flow from one section to the next, i think its a bit better, i tried to do it on this order, Intro, history, procedure, results, risks, advantages. that order seems to be how most wiki pages are set up, and how mark sets up his pages. what do you think? -Jill --[[User:Z3265772|z3265772]] 02:14, 15 September 2010 (UTC)

i think i searched prenatal diagnosis in the search box on the left, and mark has made a prenatal diagnosis page. the prenatal diagnosis terms were on that. ive been looking at last years pages, and they have so much content, but there just isnt that much information on CVS. theres only so much you can write about it. i guess we need to start thinking outside the box and adding general prenatal stuff on here too. thats why i thought maybe another table with a timeline of other techniques on it. ? ill just do it and see how it looks... -Jill --[[User:Z3265772|z3265772]] 01:47, 15 September 2010 (UTC)

hmm good idea.. btw what article did you find the terms for the prenatal diagnosis? should i incorporate that in the results section? --[[User:Z3224500|Jenny Huang]] 15:19, 14 September 2010 (UTC)

maybe we could also do ethical issues? -Jill --[[User:Z3265772|z3265772]] 12:35, 14 September 2010 (UTC)

Just an idea if we wanted to add more to the page, we could do another table, with the different diagnostic techniques used - eg ultrasound, AFP, amniocentesis and CVS etc and do a timeline with when each technique can be used, what it can test for, and how invasive it is. i know its not directly CVS, but it will give a good overview of the advantages and disadvantages etc. and im running out of ideas of what else we can have on here. can you think of anything else? -Jill --[[User:Z3265772|z3265772]] 12:30, 14 September 2010 (UTC)

Found out its due thurs, Sorry!! im doing malformations now, but we definitely need to add more content, last years pages had over 600 revisions, we only have 200. So add whatever you think we could do to improve the page. Thanks for your help over the weekend, i did feel alone in creating the page! Looks great now though! Maybe we could look at last years pages and see what we like about them, and maybe get some ideas on how to add to our page. im trying to put alot of effort in as its worth 20% of our final mark :) ive also added to the malformations part, ill keep doing that. Thanks!! -Jill --[[User:Z3265772|z3265772]] 02:24, 13 September 2010 (UTC)

Hey can't make it to lecture today.. but if its due for peer assesment today/this week, what suggestions do you think we can improve on? hmm also whos doing the part on malformations? --[[User:Z3224500|Jenny Huang]] 23:07, 12 September 2010 (UTC)

yeah good question.. ill see if i can find something more recent and let you know. i guess it would be. also, hope you dont mind, i put some of your references in, and added some pictures :) -Jill --[[User:Z3265772|z3265772]] 13:00, 12 September 2010 (UTC)

Hey for the section on malformations in current research, would it be limb defects? the articles I found were mostly from the 1990s so I'm not sure if I should use..--[[User:Z3224500|Jenny Huang]] 12:49, 12 September 2010 (UTC)

Yay it looks neat!!!glad you figured out how to fix the formatting.. It was rather confusing before haha. SOrry if it seems like you are doing most of the work :( I'll add to the current research to lighten off your load.i'll be working on it most of the weekend--[[User:Z3224500|Jenny Huang]] 16:39, 10 September 2010 (UTC)

I made a table!! it took AGES but it looks good :) we probably need to spread everything out a bit, it looks a bit crowded, but getting there! i separated the risks from current research :)- Jill --[[User:Z3265772|z3265772]] 12:03, 10 September 2010 (UTC)

Hmm it didn't take that long.. btw I've already done it but I haven't uploaded it yet but I'll do so now... hmm by the way should the heading "risks" be separate from the "current assosciated research" heading?--[[User:Z3224500|Jenny Huang]] 02:53, 10 September 2010 (UTC)

Hey! Did it take long to do the drawing for the transabdominal technique? i was thinking we could do a second one the same for transcervical. what do you think? - Jill --[[User:Z3265772|z3265772]] 02:09, 10 September 2010 (UTC)

Im pretty sure its due monday for peer assessment, thats what it says in the course guide. did he say it was due thurs in the lab last week? hope its due thurs! that would be awesome! - Jill --[[User:Z3265772|z3265772]] 12:00, 9 September 2010 (UTC)

Hey Jill, wow only 4 days! I was mistaken that it was due next thursday. But don't wrry, I'll have the whole weekend to finish up ;)--[[User:Z3224500|Jenny Huang]] 08:30, 9 September 2010 (UTC)

Hi! Ive used a reference that is not from pub med, so you can copy that to use references that arent in pub med. :) only 4 days till its due! - Jill --[[User:Z3265772|z3265772]] 01:29, 9 September 2010 (UTC)

some pictures we can use, this first one is Primary chorionic villi, the second picture is secondary chorionic villi, these may be helpful when describing the technique -Jill --[[User:Z3265772|z3265772]] 09:52, 7 September 2010 (UTC)

[[File:Gray36.png|left|400 px]]

[[File:Gray37.png|left|400 px]]

Hmm so basically we do the peer review the week after mid sem break until the 23rd of september, and we paste both the review on the groups page and on your own page... also apparently the other student discontinued the course so its just us doing the project now =S --[[User:Z3224500|Jenny Huang]] 03:02, 2 September 2010 (UTC)

Yay!! looks awesome!! Sorry i couldnt be there today, could you let me know what Mark says? thanks :) - Jill --[[User:Z3265772|z3265772]] 23:59, 1 September 2010 (UTC)

I've uploaded the first pic... I hope it's ok and if I did the layers wrongly please tell me so I can edit... also how do you do referencing that is not from pubmed journals?--[[User:Z3224500|Jenny]] 23:18, 1 September 2010 (UTC)

Hi Jenny, are you doing the drawn figure still? would you possibly be able to upload it before thursday? i have updated references for my section :) - Jill --[[User:Z3265772|z3265772]] 08:52, 1 September 2010 (UTC)

--[[User:S8600021|Mark Hill]] 00:49, 31 August 2010 (UTC) I have emailed your missing team member , but have not had a response yet. Your should continue to work on the project together as best you can. It seems to be progressing, though I did ask you to update your reference format and I do not see a student drawn figure. You need to have this updated before this weeks lab when I will be reviewing all projects.

Hi Jill, I'm working on it :) by the way have you heard from the other team member? Oh and I'll be drawing pictures for both the transcervical and transabdominal techniques..--[[User:Z3224500|Jenny Huang]] 07:46, 30 August 2010 (UTC)

Hi guys, only two weeks to go, we really need to do some more work, the editing at the end will be the hardest, so the sooner we finish, the easier it will be. - Jill--[[User:Z3265772|z3265772]] 23:46, 29 August 2010 (UTC)

Can we incorporate some sort of timeline? what do you think? maybe we can do a timeline of embryo development and note the time that CVS is done - Jill --[[User:Z3265772|z3265772]] 00:57, 26 August 2010 (UTC)

Mark has kindly shown us how to reference, ill try to sort that out tonight or tomorrow - Jill --[[User:Z3265772|z3265772]] 23:16, 25 August 2010 (UTC)

Ive just discovered, you can use almost any picture on wiki, the copyrights have usually expired, which is why wiki can use them, just search CVS on wiki and if there is a picture you like, check the copyright and copy away!! :D -Jill --[[User:Z3265772|z3265772]] 01:05, 25 August 2010 (UTC)

Hi guys, please feel free to edit any work i have done, or add to it, or even suggest to me on this page what to add. what i have put up so far really is a rough draft and will be trying to add to it later anyway :) -Jill --[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

{{Template:Projects10MHtalk}}

Hi guys, we need to get on top of this, its due for peer assessment in 3 weeks! Im going to do related research. does anyone want to do the drawing? ill also try and get some more references and photos up, as Mark has suggested. If you want a picture, just email the website with the picture on it, thats what ive been doing, they are usually pretty good about it. let me know of any other ideas you guys might have - Jill --[[User:Z3265772|z3265772]] 09:50, 23 August 2010 (UTC)

--[[User:S8600021|Mark Hill]] 04:35, 23 August 2010 (UTC) OK there are a few references here, but you will need more than these few and there should be some related images.

Link for group assessment criteria: [[2010_Lab_1#Group_Assessment_Criteria|group assessment criteria]] - Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

For current associated research:

http://onlinelibrary.wiley.com/doi/10.1002/pd.2410/abstract

http://www.ncbi.nlm.nih.gov/pubmed/11263542

http://www.ncbi.nlm.nih.gov/pubmed/19683693

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T7V-4BWVXPY-F9&_user=10&_coverDate=03%2F31%2F1994&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1427646674&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a3c3f2d47ad01c562a3baea8c60a48bc

http://www.informaworld.com/smpp/content~db=all~content=a913951525

http://www.escardiocontent.org/periodicals/ejcpr/article/S0002-9378%2807%2900305-5/abstract

http://humrep.oxfordjournals.org/cgi/content/abstract/3/6/811

- Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

Hi guys, i put up the link for Search Pubmed for our topic, did we want to assign ourselves a role to do or just see how the page goes? i thought maybe we could find a page that we like and follow a similar format, that way we know what our page will look like and can follow a layout as we go. -Jill --[[User:Z3265772|z3265772]] 01:12, 9 August 2010 (UTC)

also, see this web page http://www.cdc.gov/mmwr/preview/mmwrhtml/00038393.htm Jill --[[User:Z3265772|z3265772]] 11:16, 9 August 2010 (UTC)

project outline:

1. Intro

2. historic background

3. current associated research

4. simplified description of technique

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

5. student drawn figure or animation

6. reference list

7. glossary

8. external links

-Jill --[[User:Z3265772|z3265772]] 03:05, 11 August 2010 (UTC)

Can anyone tell me how to paste a picture from an outside source? i cant seem to figure it out. thanks :)
-Jill --[[User:Z3265772|z3265772]] 05:03, 11 August 2010 (UTC)

dont worry, i figured it out :)

i think we should put the references list on this page to begin with to make sure we dont double up
- Jill --[[User:Z3265772|z3265772]] 05:31, 11 August 2010 (UTC)

Hey guys sorry for the delay in replies. I see you have made a contribution to the topic already :) By the way, where did you find the project outline criteria? Oh and if you don't mind I can do research on the description of technique and current research. Feel free to contribute :) oh and any ideas on how to work on the drawings? --[[User:Z3224500|Jenny Huang]] 15:29, 11 August 2010 (UTC)

Hello guys,

So I found some journal articles that is of interest especially this one: http://apps.who.int/rhl/reviews/langs/CD003252.pdf which is long and has extensive information on the topic..
So I'll be editing my section in word and will be posting some info on technique in the future.

Btw here are some other articles that are of interest that can be accessed through unsw sirius:

http://linkinghub.elsevier.com/retrieve/pii/S0889854505702916

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

http://journals.lww.com/co-obgyn/Abstract/2005/04000/Chorionic_villus_sampling_and_amniocentesis.16.aspx

Complications:

http://journals.lww.com/greenjournal/Abstract/2007/09000/Procedure_Related_Complications_of_Amniocentesis.24.aspx

http://journals.lww.com/greenjournal/Abstract/2008/10000/Evaluating_the_Rate_and_Risk_Factors_for_Fetal.12.aspx

I'll be adding more once I find some that are useful..

Oh and about the topic headings are we just going to use the ones in the assesment criteria?

--[[User:Z3224500|z3224500]] 15:03, 24 August 2010 (UTC)

Hey Jenny!! i think its a great idea to use more headings, add as many as you like/can think of, i just cant think of any more. i think the assessment criteria is just the bare minimum we have to do, so please add more! Also, can we add the new discussion posts to the top of the page? so we dont have to scroll to the bottom every time? what do you think? (it says up the top of this page to add newer material at the top, just wondering what you thought). i really like the articles you have found too :) see you tomorrow
- Jill --[[User:Z3265772|z3265772]] 00:29, 25 August 2010 (UTC)

File:TranscervicalCVS.jpg

2010-09-26T22:53:35Z

Z3224500:

Transcervical procedure for CVS. A fine cannula is inserted into the vagina and chorionic tissue is withdrawn.

"Beginning six months after publication, I (z) grant the public the non-exclusive right to copy, distribute, or display the Work under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/ and http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode." --[[User:Z3224500|z3224500]] 22:53, 26 September 2010 (UTC)

File:Transabdominal CVS.jpg

2010-09-26T22:52:17Z

Z3224500:

The Transabdominal procedure for chorionic villus sampling (CVS). A hollow needle is passed through to the placenta and a sample of the villi from the chorion is taken for testing.

"Beginning six months after publication, I (z) grant the public the non-exclusive right to copy, distribute, or display the Work under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/ and http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode."
--[[User:Z3224500|z3224500]] 22:52, 26 September 2010 (UTC)

Talk:2010 Group Project 2

2010-09-26T22:11:03Z

Z3224500:

Umm.. I'm not sure about that, because the sources I found mosaicism on had it in their "limitations" heading... --[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)--[[User:Z3224500|Jenny Huang]] 22:11, 26 September 2010 (UTC)

Hey Jenny, do you think Mosaicism should be in the abnormalities found by CVS section? a few people have commented that its a bit confusing what the test detects and the risks associated with testing. i think Mosaicism is more under the heading of what cvs detects --[[User:Z3265772|z3265772]] 04:16, 23 September 2010 (UTC)

hey jill,
group 6 here, you may use our picture

--[[User:Z3254433|z3254433]] 09:07, 26 September 2010 (UTC)

===to fix===

'''Begin''' by collating the comments.
* What are the common criticisms?
* What were the best aspects identified within your project?
* What errors, typos, missing references were identified?
* Were there contributions from individual group members that were identified as good or poor parts of the overall project?

'''Then''' work on the changes.
* Develop priorities.
* Divide the changes and corrections between group members.
* Are there additional changes that should be made that were not identified by peer assessment.

'''Jill:'''

abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? comparative genomics, Improvements?

future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether

DONE move glossary above references so you dont have to scroll all the way down to read them

DONE table comparing other techniques

DONE got confused between the risks of this test and what it predicted (this will be clear in the above table)

DONE -it didn't state that the test was invasive in intro (table)

DONE -All spelling amd grammar - some more editing of spelling is required

DONE "abnormalities found by CVS" section towards the top of the page coz I got confused between the risks of this test and what it predicted

DONE -link or a reference to the brief time line where you state the names of the authors

DONE -The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed

DONE -I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources

DONE -a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work

DONE - it would be that you put the advantages/disadvantages of CVS over other techniques in a table.

'''Jenny:'''

flowchart or more pictures of procedure

clarify what hypertension is in the hypertensive disorders of pregnancy section

possibly more pictures or a flowchart of the procedure itself?

outcomes + ethics,

Are the transabdominal and the transcervical pictures the student-drawn ones? put up in discussion that you drew them and you give permission for re-use - Jenny, ive done this for you, all you need to do is edit and add your student number, -Jill

elaborate on procedure eg what cells are being taken etc and stages of chorionic villus in embryology

Spelling and grammar, - Jenny, ive gone through the page and edited the spelling mistakes i could find, could you please do the same incase ive missed any? and double check the sections you are about to write? Thanks :) - Jill --[[User:Z3265772|z3265772]] 00:33, 24 September 2010 (UTC)

The current research section could be put more into point form to make it more inviting to read - not sure if you want to do this, i think its ok as it is, maybe just delete this suggestion? or add pictures of people researching? haha

----

==Peer Review==

'''Please note!''' when posting your peer review, we only have two group members. the other one dropped out. Thanks :)

--[[User:Z3129413]] 16:29, 22 September 2010 (UTC)
I love those old timey pencil medical pictures and so for me this was really great, what instantly nailed the whole positive immediate impression was 'Reasons for getting chorionic villus sampling etc etc' right there at the beginning. Why would I get one? thanks very much. Perhaps a darker font would make it even better. Historical back ground is really good and technique pictures are of high standard. The table presentation of abnormalities found and ratios is such an effective way of portraying this information.

A few Q's with the hypertension cvs topic,
Is there a normally expected percent of women in a large population to develop hypertensive disorders, just for perspective? CVS would not lower incidences of such surely (9098 pop, 2.7% to 7.1% control). 138 study size seems a bit low, is result really much more significant? However I did understand that CVS was more risk prone than amniocentesis for pre eclampsia and gestational hypertension.
This project is well on track.

Group 2: Your project is very impressive in content as well as organisation. The most notable thing for me was the wide use of pictures which must have taken a lot of time and effort to source. They definitely create an engaging page especially in conjunction with the use of tables and clear subheadings. The structure you have used is very effective as it allows your information to be scientific and thorough but at the same time it is concise and easy to navigate. I felt like i got an extensive overview of CVS after having read your page and the use of pictures and subheadings kept it from being a chore. I felt the history and abnormalities sections were particularly interesting. I also appreciate how you have seemed to approach this topic from all angles and not just a one-sided, all current and positive viewpoint. To improve your page perhaps you could explore the future role of CVS in prenatal diagnosis or even the role of invasive procedures altogether. Either way your page is probably up to standard as it is and it is obvious that you have worked hard at it. Job well done.
--[[User:Z3293029|z3293029]] 14:38, 22 September 2010 (UTC)

Group 2: fantastic use of images, it definitely worked to your advantage in engaging your audience's attention. Over all the language used is relatively easy to follow yet informative. As someone has already mentioned, some more editing of spelling is required. The amount of attention to detail is evident in the references which are from a range of sources so well done. I particularly liked that the page covered accuracy and limitations of the diagnostic procedure. Something that lacked clarity in a few other groups. Good use of the table covering the abnormalities, maybe just adjust the cells of the table a little so the spacing appears more even as some cells have very little content while others are completely filled. What about the future of CVS? Is it a procedure that is going to continue as simply diagnostic? Is it being superseded by another procedure? Improvements?
Just an idea. Well done overall. --z3241780 13:40, 22 September 2010 (UTC)

'''GROUP 2: Chorionic Villi Sampling'''

This page caught my attention as soon as I saw it and that made me want to read on and thus learn about Chorionic Villi Sampling. A lot of research has gone into this assignment and it’s evident in the information presented as its precise which also helps capture the readers. The amount of research is also evident in the long list of references. The webpage is actually extremely informative covering pretty much every aspect of the pre-natal diagnostic techniques. Your webpage has the most pictures and this helps it stand out as one of the best project pages. I really, really like the formatting and the tables. The images break up the information so you’re never overloaded with the amount of text. The only bit of criticism is spelling but this is extremely minor as you’ll pick up on the spelling mistakes when you go over the page. The language in is the right mixture of scientific language meaning that even people without a scientific background can understand the CVS. Great job guys you really can’t tell that only two people are in this group. It’s extremely good!!! I also really like the first picture you have, gives a page a really good feel to it.

--[[User:Z3252635|z3252635]] 13:20, 22 September 2010 (UTC)

Hi guys!

You have found so many great pictures! Your page looks amazing. I just wonder where the files came from – I saw you put up the copyright notices, but I couldn’t find the file sources. Your timeline was great too; I really like how you put up the concise timeline and then expanded a bit on the major developments afterwards. Are the transabdominal and the transcervical pictures the student-drawn ones? If so, well done! They’re really clear and beautifully done, but you should probably label them as student drawn and put in the copyright statement. If I could suggest something, it would be that you put the advantages/disadvantages of CVS over other techniques in a table. Otherwise, your page is really easy to read, and again has brilliant visuals – great job!--[[User:Z3252833|z3252833]] 12:42, 22 September 2010 (UTC)

CVS.

Group 2, your project is looking great, the first thing i noticed when reading it is that there is lots of detail which shows a great depth of research has gone into it, which is supported by your reference list. Another thing is the amount of pictures which support the information and break it up to make it easier to take in so much information at once. The disorders table provides great detail and makes it interesting with the pictures.

What could be improved: You could put the advantages/disadvantages into a table form to make it even easier to understand. The reasons to use this technique could be slotted into the procedure section instead of the introduction maybe as it shows who is eligible for the procedure. The current research section could be put more into point form to make it more inviting to read. But overall really great project.

--[[User:Z3292208|z3292208]] 08:55, 22 September 2010 (UTC)

This project is extremely well done. It seems a great effort has gone into proper referencing which also gives the impression of a thoughtful attempt. The balance of information mediums is great and the logical flow of ideas when reading through each section is perfect.
Suggestion: possibly more pictures or a flowchart of the procedure itself?

Well done :)

--[[User:Z3254753|z3254753]] 16:55, 21 September 2010 (UTC)

Group 2- This project had tons of photos which is super great because its much easier to follow... Most of the point made is supported with pictures ..definetly provided me a better understanding of CVS ..I agree with what others have mentioned its very informative and especially with just 2 team members .. fantastic work

what could be improved = a little more reference in the "result and accuracy" section since it includes some percentage other than that fantastic work ..--[[User:Z3305561|Navneet Ahuja]] 12:53, 21 September 2010 (UTC)

Group project 2: chorionic villus sampling

This group had great images and the page layout was good too especially the tables which simplified the information and made it easier to read. The information presented was very informative, scientific, and all the key concepts were covered on the topic. The project had a very impressive reference list, and it did help in my understanding of this prenatal diagnostic technique.

What could be improved?
I did find a spelling mistake under the heading Results and Accuracy were you have written “maybe” instead of “baby”, so maybe proof read the assignment to pick up on any other possible spelling or grammatical errors, other than that well done.

--[[User:Z3254433|z3254433]] 07:15, 20 September 2010 (UTC)

This project was highly informative about CVS. It contained a lot of information in which it shows that a lot of research has gone into it. Everything has been covered like, what the test predicts and what risks are associated with this test. It was very scientific, yet easy to understand at a non-scientific level. I liked the external links how it directed me straight to a page of different articles about CVS.

What could be improved is maybe placing the "abnormalities found by CVS" section towards the top of the page, because i was a bit unsure on what this test predicted in the first place. I got confused between the risks of this test and what it predicted. But I managed to understand it all once all read through. Also, a definition of a "cannula" may be helpful in the glossary too, i wasn't sure what that exactly was.

--[[User:Z3291079|z3291079]] 02:48, 21 September 2010 (UTC)

This project provides a clear understanding of the key information regarding CVS, such as how it is carried out, the risks and benfits of CVS, what it is used for as well as future research. I have find the pictures to be of a great help in explaining the procedure of CVS.

One think I did notice was that, it didn't state that the test was invasive until you figure it out when you look at the pictures in the procedures. I think stating that in the introduction would make it clearer for readers to follow on with the information this projects provides having that knowledge in mind at the start.

--[[User:Z3216889|3216889]] 12:13, 22 September 2010 (UTC)

This web page is definitely one of my favorites. The information that you have provided is exceptional; the reference list is indicative of your extensive research. The table of deformities was a stand out for me as it was very well set out and was a effective break from the text. You also used excellent external links that were very well placed within the web page. A slight improvement would be to include a link or a reference to the brief time line where you state the names of the authors, and as previously mentioned, reference the statistics that you have included. Other than that, I applaud you for a job well done!--[[User:Z3252083|z3252083]] 12:22, 22 September 2010 (UTC)

--Group 2 Chronic villus sampling
This webpage shows that the group was very thorough in the research due to the amount of detail that has gone into it and its many links. The layout is very well set out which helps someone understand it if he/she has no previous knowledge of the concept. The use of pictures and diagrams were done well as it broke the page up making it very easy to read and take in the information. The only advice I can give is to maybe separate the difference between normal and abnormal chromosomes and the adjacent table to allow the table more room and be easily viewed. That’s all guys and well done considering you only had 2 people working on it.

--[[User:Z3290040|3290040]] 10:19, 22 September 2010 (UTC)

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----

===group discussion===

I agree the page feels more "in order" now. yeh... its tough trying to find more information. I guess i'll expand on maybe on some of the abnormalities? I was thinking we can get pictures of the several diseases but it will probably be a little difficult due to copyright? hmm if i get new ideas from now until tommorrow i'll definately add more stuff in --[[User:Z3224500|Jenny Huang]] 06:38, 15 September 2010 (UTC)

Hey Jenny, i changed the order of the page around, i think it makes more sense now, before it didnt really flow from one section to the next, i think its a bit better, i tried to do it on this order, Intro, history, procedure, results, risks, advantages. that order seems to be how most wiki pages are set up, and how mark sets up his pages. what do you think? -Jill --[[User:Z3265772|z3265772]] 02:14, 15 September 2010 (UTC)

i think i searched prenatal diagnosis in the search box on the left, and mark has made a prenatal diagnosis page. the prenatal diagnosis terms were on that. ive been looking at last years pages, and they have so much content, but there just isnt that much information on CVS. theres only so much you can write about it. i guess we need to start thinking outside the box and adding general prenatal stuff on here too. thats why i thought maybe another table with a timeline of other techniques on it. ? ill just do it and see how it looks... -Jill --[[User:Z3265772|z3265772]] 01:47, 15 September 2010 (UTC)

hmm good idea.. btw what article did you find the terms for the prenatal diagnosis? should i incorporate that in the results section? --[[User:Z3224500|Jenny Huang]] 15:19, 14 September 2010 (UTC)

maybe we could also do ethical issues? -Jill --[[User:Z3265772|z3265772]] 12:35, 14 September 2010 (UTC)

Just an idea if we wanted to add more to the page, we could do another table, with the different diagnostic techniques used - eg ultrasound, AFP, amniocentesis and CVS etc and do a timeline with when each technique can be used, what it can test for, and how invasive it is. i know its not directly CVS, but it will give a good overview of the advantages and disadvantages etc. and im running out of ideas of what else we can have on here. can you think of anything else? -Jill --[[User:Z3265772|z3265772]] 12:30, 14 September 2010 (UTC)

Found out its due thurs, Sorry!! im doing malformations now, but we definitely need to add more content, last years pages had over 600 revisions, we only have 200. So add whatever you think we could do to improve the page. Thanks for your help over the weekend, i did feel alone in creating the page! Looks great now though! Maybe we could look at last years pages and see what we like about them, and maybe get some ideas on how to add to our page. im trying to put alot of effort in as its worth 20% of our final mark :) ive also added to the malformations part, ill keep doing that. Thanks!! -Jill --[[User:Z3265772|z3265772]] 02:24, 13 September 2010 (UTC)

Hey can't make it to lecture today.. but if its due for peer assesment today/this week, what suggestions do you think we can improve on? hmm also whos doing the part on malformations? --[[User:Z3224500|Jenny Huang]] 23:07, 12 September 2010 (UTC)

yeah good question.. ill see if i can find something more recent and let you know. i guess it would be. also, hope you dont mind, i put some of your references in, and added some pictures :) -Jill --[[User:Z3265772|z3265772]] 13:00, 12 September 2010 (UTC)

Hey for the section on malformations in current research, would it be limb defects? the articles I found were mostly from the 1990s so I'm not sure if I should use..--[[User:Z3224500|Jenny Huang]] 12:49, 12 September 2010 (UTC)

Yay it looks neat!!!glad you figured out how to fix the formatting.. It was rather confusing before haha. SOrry if it seems like you are doing most of the work :( I'll add to the current research to lighten off your load.i'll be working on it most of the weekend--[[User:Z3224500|Jenny Huang]] 16:39, 10 September 2010 (UTC)

I made a table!! it took AGES but it looks good :) we probably need to spread everything out a bit, it looks a bit crowded, but getting there! i separated the risks from current research :)- Jill --[[User:Z3265772|z3265772]] 12:03, 10 September 2010 (UTC)

Hmm it didn't take that long.. btw I've already done it but I haven't uploaded it yet but I'll do so now... hmm by the way should the heading "risks" be separate from the "current assosciated research" heading?--[[User:Z3224500|Jenny Huang]] 02:53, 10 September 2010 (UTC)

Hey! Did it take long to do the drawing for the transabdominal technique? i was thinking we could do a second one the same for transcervical. what do you think? - Jill --[[User:Z3265772|z3265772]] 02:09, 10 September 2010 (UTC)

Im pretty sure its due monday for peer assessment, thats what it says in the course guide. did he say it was due thurs in the lab last week? hope its due thurs! that would be awesome! - Jill --[[User:Z3265772|z3265772]] 12:00, 9 September 2010 (UTC)

Hey Jill, wow only 4 days! I was mistaken that it was due next thursday. But don't wrry, I'll have the whole weekend to finish up ;)--[[User:Z3224500|Jenny Huang]] 08:30, 9 September 2010 (UTC)

Hi! Ive used a reference that is not from pub med, so you can copy that to use references that arent in pub med. :) only 4 days till its due! - Jill --[[User:Z3265772|z3265772]] 01:29, 9 September 2010 (UTC)

some pictures we can use, this first one is Primary chorionic villi, the second picture is secondary chorionic villi, these may be helpful when describing the technique -Jill --[[User:Z3265772|z3265772]] 09:52, 7 September 2010 (UTC)

[[File:Gray36.png|left|400 px]]

[[File:Gray37.png|left|400 px]]

Hmm so basically we do the peer review the week after mid sem break until the 23rd of september, and we paste both the review on the groups page and on your own page... also apparently the other student discontinued the course so its just us doing the project now =S --[[User:Z3224500|Jenny Huang]] 03:02, 2 September 2010 (UTC)

Yay!! looks awesome!! Sorry i couldnt be there today, could you let me know what Mark says? thanks :) - Jill --[[User:Z3265772|z3265772]] 23:59, 1 September 2010 (UTC)

I've uploaded the first pic... I hope it's ok and if I did the layers wrongly please tell me so I can edit... also how do you do referencing that is not from pubmed journals?--[[User:Z3224500|Jenny]] 23:18, 1 September 2010 (UTC)

Hi Jenny, are you doing the drawn figure still? would you possibly be able to upload it before thursday? i have updated references for my section :) - Jill --[[User:Z3265772|z3265772]] 08:52, 1 September 2010 (UTC)

--[[User:S8600021|Mark Hill]] 00:49, 31 August 2010 (UTC) I have emailed your missing team member , but have not had a response yet. Your should continue to work on the project together as best you can. It seems to be progressing, though I did ask you to update your reference format and I do not see a student drawn figure. You need to have this updated before this weeks lab when I will be reviewing all projects.

Hi Jill, I'm working on it :) by the way have you heard from the other team member? Oh and I'll be drawing pictures for both the transcervical and transabdominal techniques..--[[User:Z3224500|Jenny Huang]] 07:46, 30 August 2010 (UTC)

Hi guys, only two weeks to go, we really need to do some more work, the editing at the end will be the hardest, so the sooner we finish, the easier it will be. - Jill--[[User:Z3265772|z3265772]] 23:46, 29 August 2010 (UTC)

Can we incorporate some sort of timeline? what do you think? maybe we can do a timeline of embryo development and note the time that CVS is done - Jill --[[User:Z3265772|z3265772]] 00:57, 26 August 2010 (UTC)

Mark has kindly shown us how to reference, ill try to sort that out tonight or tomorrow - Jill --[[User:Z3265772|z3265772]] 23:16, 25 August 2010 (UTC)

Ive just discovered, you can use almost any picture on wiki, the copyrights have usually expired, which is why wiki can use them, just search CVS on wiki and if there is a picture you like, check the copyright and copy away!! :D -Jill --[[User:Z3265772|z3265772]] 01:05, 25 August 2010 (UTC)

Hi guys, please feel free to edit any work i have done, or add to it, or even suggest to me on this page what to add. what i have put up so far really is a rough draft and will be trying to add to it later anyway :) -Jill --[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

{{Template:Projects10MHtalk}}

Hi guys, we need to get on top of this, its due for peer assessment in 3 weeks! Im going to do related research. does anyone want to do the drawing? ill also try and get some more references and photos up, as Mark has suggested. If you want a picture, just email the website with the picture on it, thats what ive been doing, they are usually pretty good about it. let me know of any other ideas you guys might have - Jill --[[User:Z3265772|z3265772]] 09:50, 23 August 2010 (UTC)

--[[User:S8600021|Mark Hill]] 04:35, 23 August 2010 (UTC) OK there are a few references here, but you will need more than these few and there should be some related images.

Link for group assessment criteria: [[2010_Lab_1#Group_Assessment_Criteria|group assessment criteria]] - Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

For current associated research:

http://onlinelibrary.wiley.com/doi/10.1002/pd.2410/abstract

http://www.ncbi.nlm.nih.gov/pubmed/11263542

http://www.ncbi.nlm.nih.gov/pubmed/19683693

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T7V-4BWVXPY-F9&_user=10&_coverDate=03%2F31%2F1994&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1427646674&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a3c3f2d47ad01c562a3baea8c60a48bc

http://www.informaworld.com/smpp/content~db=all~content=a913951525

http://www.escardiocontent.org/periodicals/ejcpr/article/S0002-9378%2807%2900305-5/abstract

http://humrep.oxfordjournals.org/cgi/content/abstract/3/6/811

- Jill--[[User:Z3265772|z3265772]] 00:50, 25 August 2010 (UTC)

Hi guys, i put up the link for Search Pubmed for our topic, did we want to assign ourselves a role to do or just see how the page goes? i thought maybe we could find a page that we like and follow a similar format, that way we know what our page will look like and can follow a layout as we go. -Jill --[[User:Z3265772|z3265772]] 01:12, 9 August 2010 (UTC)

also, see this web page http://www.cdc.gov/mmwr/preview/mmwrhtml/00038393.htm Jill --[[User:Z3265772|z3265772]] 11:16, 9 August 2010 (UTC)

project outline:

1. Intro

2. historic background

3. current associated research

4. simplified description of technique

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

5. student drawn figure or animation

6. reference list

7. glossary

8. external links

-Jill --[[User:Z3265772|z3265772]] 03:05, 11 August 2010 (UTC)

Can anyone tell me how to paste a picture from an outside source? i cant seem to figure it out. thanks :)
-Jill --[[User:Z3265772|z3265772]] 05:03, 11 August 2010 (UTC)

dont worry, i figured it out :)

i think we should put the references list on this page to begin with to make sure we dont double up
- Jill --[[User:Z3265772|z3265772]] 05:31, 11 August 2010 (UTC)

Hey guys sorry for the delay in replies. I see you have made a contribution to the topic already :) By the way, where did you find the project outline criteria? Oh and if you don't mind I can do research on the description of technique and current research. Feel free to contribute :) oh and any ideas on how to work on the drawings? --[[User:Z3224500|Jenny Huang]] 15:29, 11 August 2010 (UTC)

Hello guys,

So I found some journal articles that is of interest especially this one: http://apps.who.int/rhl/reviews/langs/CD003252.pdf which is long and has extensive information on the topic..
So I'll be editing my section in word and will be posting some info on technique in the future.

Btw here are some other articles that are of interest that can be accessed through unsw sirius:

http://linkinghub.elsevier.com/retrieve/pii/S0889854505702916

http://journals.lww.com/co-obgyn/Abstract/2010/04000/Chorionic_villus_sampling__technique_and_training.11.aspx

http://journals.lww.com/co-obgyn/Abstract/2005/04000/Chorionic_villus_sampling_and_amniocentesis.16.aspx

Complications:

http://journals.lww.com/greenjournal/Abstract/2007/09000/Procedure_Related_Complications_of_Amniocentesis.24.aspx

http://journals.lww.com/greenjournal/Abstract/2008/10000/Evaluating_the_Rate_and_Risk_Factors_for_Fetal.12.aspx

I'll be adding more once I find some that are useful..

Oh and about the topic headings are we just going to use the ones in the assesment criteria?

--[[User:Z3224500|z3224500]] 15:03, 24 August 2010 (UTC)

Hey Jenny!! i think its a great idea to use more headings, add as many as you like/can think of, i just cant think of any more. i think the assessment criteria is just the bare minimum we have to do, so please add more! Also, can we add the new discussion posts to the top of the page? so we dont have to scroll to the bottom every time? what do you think? (it says up the top of this page to add newer material at the top, just wondering what you thought). i really like the articles you have found too :) see you tomorrow
- Jill --[[User:Z3265772|z3265772]] 00:29, 25 August 2010 (UTC)