BGDA Practical Placenta - Abnormalities: Difference between revisions

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* Preeclampsia - describes maternal high blood pressure and protein in the urine after the 20th week (GA) late 2nd or 3rd trimester of pregnancy. This may be due to factors from the placenta.
* Preeclampsia - describes maternal high blood pressure and protein in the urine after the 20th week (GA) late 2nd or 3rd trimester of pregnancy. This may be due to factors from the placenta.
* Eclampsia - seizures (convulsions) in a pregnant woman that are not related to a preexisting brain condition.
* Eclampsia - seizures (convulsions) in a pregnant woman that are not related to a preexisting brain condition.
'''Royal Hospital for Women'''
* [http://www.sesiahs.health.nsw.gov.au/rhw/Manuals/documents/Delivery/Placental%20Examination%20Guideline.pdf Placental Examination PDF]
* [http://www.sesiahs.health.nsw.gov.au/rhw/Manuals/documents/Antenatal_Pregnancy%20Care/Placenta%20Praevia.pdf Placenta Praevia PDF]





Revision as of 01:45, 4 June 2012

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Practical 14: Implantation and Early Placentation | Villi Development | Maternal Decidua | Cord Development | Placental Functions | Diagnostic Techniques | Abnormalities



Content to be added.

Hydatidiform Mole

Hydatidiform Mole

Another type of abnormality is when only the conceptus trophoblast layers proliferates and not the embryoblast, no embryo develops, this is called a "hydatidiform mole" (HM), which is due to the continuing presence of the trophoblastic layer, this abnormal conceptus can also implant in the uterus. The trophoblast cells will secrete human chorionic gonadotropin (hCG), as in a normal pregnancy, and may appear maternally and by pregnancy test to be "normal". Prenatal diagnosis by ultrasound analysis demonstrates the absence of a embryo.

There are several forms of hydatidiform mole: partial mole, complete mole and persistent gestational trophoblastic tumor. Many of these tumours arise from a haploid sperm fertilizing an egg without a female pronucleus (the alternative form, an embryo without sperm contribution, is called parthenogenesis). The tumour has a "grape-like" placental appearance without enclosed embryo formation. Following a first molar pregnancy, there is approximately a 1% risk of a second molar pregnancy.

  • The incidence of hydatidiform mole varies between ethnic groups, and typically occurs in 1 in every 1500 pregnancies.
  • All hydatidiform mole cases are sporadic, except for extremely rare familial cases.
  • A maternal gene has been identified for recurrent hydatidiform mole (chromosome 19q13.3-13.4 in a 15.2 cM interval flanked by D19S924 and D19S890).[1]


Links: Hydatidiform Mole | Week 2 - Abnormalities

Implantation Abnormalities

Placenta abnormalities.jpg


The placenta is a mateno-fetal organ which begins developing at implantation of the blastocyst and is delivered with the fetus at birth. As the fetus relies on the placenta for not only nutrition, but many other developmentally essential functions, the correct development of the placenta is important to correct embryonic and fetal development.

Abnormalities can range from anatomical associated with degree or site of inplantation, structure (as with twinning), to placental function, placento-maternal effects (pre-eclampsia, fetal erythroblastosis) and finally mechanical abnormalities associated with the placental (umbilical) cord.

  • Placenta Accreta - abnormal adherence, with absence of decidua basalis. The incidence of placenta accreta also significantly increases in women with previous cesarean section compared to those without a prior surgical delivery.
  • Placenta Increta - occurs when the placenta attaches deep into the uterine wall and penetrates into the uterine muscle, but does not penetrate the uterine serosa. Placenta increta accounts for approximately 15-17% of all cases.
  • Placenta Percreta - placental villi penetrate myometrium and through to uterine serosa.
  • Placenta Previa - In this placenatal abnormality, the placenta overlies internal os of uterus, essentially covering the birth canal. This condition occurs in approximately 1 in 200 to 250 pregnancies. In the third trimester and at term, abnormal bleeding can require cesarian delivery and can also lead to Abruptio Placenta. Ultrasound screening programs during 1st and early 2nd trimester pregnancies now include placental localization. Diagnosis can also be made by transvaginal ultrasound.
  • Vasa Previa - (vasa praevia) placental abnormality where the fetal vessels lie within the membranes close too or crossing the inner cervical os (opening). This occurs normally in 1:2500-5000 pregnancies and leads to complications similar too those for Placenta Previa.Type II is defined as the condition where the fetal vessels are found crossing over the internal os connecting either a bilobed placenta or a succenturiate lobe with the main placental mass. Some recent evidence of successful in utero laser ablation of type II vasa previa at 22.5 weeks of gestation.
  • Abruptio Placenta - a retroplacental blood clot formation, abnormal hemorrhage prior to delivery.
  • Chronic Intervillositis - (massive chronicintervillositis, chronic histiocytic intervillositis) Rare placental abnormality and pathology defined by inflammatory placental lesions, mainly in the intervillous space (IVS), with a maternal infiltrate of mononuclear cells (monocytes, lymphocytes, histiocytes) and intervillous fibrinoid deposition.

Cord Abnormalities

Cord Vessel Number

Placental cord ultrasound 02.jpg

Cord with only one artery and one vein.

Cord Knotting

Placental cord true knot

There are few abnormalities associated with umbilical cord development, other that abnormally short or long cords, which in most cases do not cause difficulties.

In some cases though, long cords can wrap around limbs or the fetus neck, which can then restrict blood flow or lead to tissue or nerve damage, and therefore effect develoment.

Cord knotting can also occur (1%) in most cases these knots have no effect, in some cases of severe knotting this can prevents the passage of placental blood.

Umbilical cord torsion

Rare umbilical cord torsion, even without knot formation can also affect placental blood flow, even leading to fetal demise.


Cord Length

Excessively short or long cords.


Additional Information

  • Preeclampsia - describes maternal high blood pressure and protein in the urine after the 20th week (GA) late 2nd or 3rd trimester of pregnancy. This may be due to factors from the placenta.
  • Eclampsia - seizures (convulsions) in a pregnant woman that are not related to a preexisting brain condition.

Royal Hospital for Women


<pubmed>9518951</pubmed>| Am Fam Physician.

"A one-minute examination of the placenta performed in the delivery room provides information that may be important to the care of both mother and infant. The findings of this assessment should be documented in the delivery records. During the examination, the size, shape, consistency and completeness of the placenta should be determined, and the presence of accessory lobes, placental infarcts, hemorrhage, tumors and nodules should be noted. The umbilical cord should be assessed for length, insertion, number of vessels, thromboses, knots and the presence of Wharton's jelly. The color, luster and odor of the fetal membranes should be evaluated, and the membranes should be examined for the presence of large (velamentous) vessels. Tissue may be retained because of abnormal lobation of the placenta or because of placenta accreta, placenta increta or placenta percreta. Numerous common and uncommon findings of the placenta, umbilical cord and membranes are associated with abnormal fetal development and perinatal morbidity. The placenta should be submitted for pathologic evaluation if an abnormality is detected or certain indications are present."

Terms

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Cite this page: Hill, M.A. (2024, March 29) Embryology BGDA Practical Placenta - Abnormalities. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDA_Practical_Placenta_-_Abnormalities

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
  1. <pubmed>10072436</pubmed>