|Embryology - 17 Jan 2019 Expand to Translate|
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| Amniocentesis is a prenatal diagnostic test carried out mainly between 14th to 18th week of pregnancy (GA week 14 to 18).
In amniocentesis, amniotic fluid is taken from the uterus, sent to a diagnostic laboratory and embryonic cells isolated from the amniotic fluid. No anaesthetic is required, and a result is usually obtained in about three to four weeks. When the test is carried out by an obstetrician experienced in the technique, the risk of a miscarriage related to the test can be about 1 %. A recent study of the published literature, showed a procedure-related risk of miscarriage following amniocentesis was 0.35% (95% confidence interval [CI]: 0.07 to 0.63).. A more detailed Cochrane review of amniocentesis and chorionic villus sampling has also bee carried out. This technique has not yet been fully replaced for primary screening by cell-free DNA analysis.Placenta - Amnionic Sac
Some Recent Findings
|More recent papers|
This table allows an automated computer search of the external PubMed database using the listed "Search term" text link.
A Chochrane review (2003) comparing prenatal diagnosis showed that early amniocentesis is not a safe as mid-trimester amniocentesis or chorionic villus sampling, because of increased pregnancy loss and the increased risk of Talipes equinovarus.
Cells floating in the fluid can be isolated for genetic analysis and the amniotic fluid can also be often assessed for both quality and quantity. The amniotic fluid volume increases as the fetus grows and rate of change varies during the pregnancy.
- up to 8 weeks - increases at the rate of 10 ml/week
- 8 to 13 weeks - increases at the rate of 25 ml/week
- 13 to 21 weeks - increases at the rate of 60 ml/week
- 21 to 33 weeks - amniotic volume increase starts decreasing and eventually plateaus.
- 34 weeks (GA) - peaks at about 800 mL.
- 40 weeks (GA) - about 600 mL at term.
- Circulated by fetal inhaling and swallowing.
- Replaced by fetal exhalation and urination.
- Magnesium low levels associated with preeclampsia and diabetes.
- normal magnesium value at 16 weeks (GA) is 1.65 ± 0.16 mg/dL in amniotic fluid and 1.97 ± 0.23 mg/dL in serum.
Amniotic Fluid Stem Cells
It has been shown that human amniotic fluid stem cells (hAFSCs) can be retrieved directly from a small amount of mid-term pregnancy amniotic fluid that can be obtained at the time of diagnostic amniocentesis. These are generally considered as mesenchymal stem cells.
- Links: Stem Cell
A typical example of ultrasound guided amniotic fluid sampling (amniocentesis) at 16 weeks of pregnancy (Royal Berkshire, Published on Oct 21, 2013).
First used as a test of fetal sex in 1955Serr DM, Sachs L & Danon M. (1955). The diagnosis of sex before birth using cells from the amniotic fluid (a preliminary report). Bull Res Counc Isr , 5B, 137-8. PMID: 12307916 , two years later in 1957 was then published as a wider prenatal diagnostic test.
- Beta J, Lesmes-Heredia C, Bedetti C & Akolekar R. (2018). Risk of miscarriage following amniocentesis and chorionic villus sampling: a systematic review of the literature. Minerva Ginecol , 70, 215-219. PMID: 29161799 DOI.
- Alfirevic Z, Navaratnam K & Mujezinovic F. (2017). Amniocentesis and chorionic villus sampling for prenatal diagnosis. Cochrane Database Syst Rev , 9, CD003252. PMID: 28869276 DOI.
- Gray KJ & Wilkins-Haug LE. (2018). Have we done our last amniocentesis? Updates on cell-free DNA for Down syndrome screening. Pediatr Radiol , 48, 461-470. PMID: 29550862 DOI.
- Kim SR, Choi EJ, Kim YJ, Kim TY & Lee YJ. (2018). Prenatally Diagnosed Rare Trisomy 16 Mosaicism in Human Amniotic Fluid Cells in the Second Trimester: A Case Report. Dev Reprod , 22, 199-203. PMID: 30023470 DOI.
- Geffen KT, Ben-Zvi O, Weitzner O, Peleg A, Biron-Shental T & Sukenik-Halevy R. (2017). The yield and complications of amniocentesis performed after 24 weeks of gestation. Arch. Gynecol. Obstet. , 296, 69-75. PMID: 28540575 DOI.
- Orczyk-Pawilowicz M, Jawien E, Deja S, Hirnle L, Zabek A & Mlynarz P. (2016). Metabolomics of Human Amniotic Fluid and Maternal Plasma during Normal Pregnancy. PLoS ONE , 11, e0152740. PMID: 27070784 DOI.
- Oh KJ, Park JS, Norwitz ER, Kim SM, Kim BJ, Park CW, Jun JK & Syn HC. (2012). Proteomic biomarkers in second trimester amniotic fluid that identify women who are destined to develop preeclampsia. Reprod Sci , 19, 694-703. PMID: 22534327 DOI.
- Visnjevac J, Mikić AN, Nikolić A & Visnjevac N. (2010). [Comparative analysis of amniotic fluid lamellar body count and foam stability test as indices of fetal lung maturity]. Med. Pregl. , 63, 747-52. PMID: 21553448
- Weisz B, Book M, Lipitz S, Katorza E, Achiron R, Grossman Z & Shrim A. (2011). Fetal outcome and amniocentesis results in pregnancies complicated by varicella infection. J Obstet Gynaecol Can , 33, 720-724. PMID: 21749748 DOI.
- McIntosh JJ, McHugh K & Haas DM. (2012). Difficulties in establishing routine amniocentesis for preterm labor evaluation. J. Matern. Fetal. Neonatal. Med. , 25, 313-4. PMID: 21663523 DOI.
- Alfirevic Z, Sundberg K & Brigham S. (2003). Amniocentesis and chorionic villus sampling for prenatal diagnosis. Cochrane Database Syst Rev , , CD003252. PMID: 12917956 DOI.
- Bocos Terraz JP, Izquierdo Álvarez S, Bancalero Flores JL, González López A & Escanero Marcén JF. (2011). Magnesium concentration in amniotic fluid in the early weeks of the second trimester of pregnancy. BMC Res Notes , 4, 185. PMID: 21672230 DOI.
- PARRISH HM, LOCK FR & ROUNTREE ME. (1957). Lack of congenital malformations in normal human pregnancies after transabdominal amniocentesis. Science , 126, 77. PMID: 13442649
Evans MI, Wapner RJ. Invasive prenatal diagnostic procedures 2005. Semin Perinatol. 2005 Aug;29(4):215-8.
Ball RH. Invasive fetal testing. Curr Opin Obstet Gynecol. 2004 Apr;16(2):159-62.
- ART - Assisted Reproductive Technology a general term to describe all the clinical techniques used to aid fertility.
- blastomere biopsy - An ART preimplantation genetic diagnosis technique carried out at cleavage stage (day 3), excluding poor quality embryos, detects chromosomal abnormalities of both maternal and paternal origin. May not detect cellular mosaicism in the embryo.
- blastocyst biopsy - An ART preimplantation genetic diagnosis technique carried out at blastocyst stage (day 4-5), removes several trophoblast (trophoderm) cells, detects chromosomal abnormalities of both maternal and paternal origin and may detect cellular mosaicism.
- cell-free fetal deoxyribonucleic acid - (cffDNA) refers to fetal DNA circulating and isolated from the plasma portion of maternal blood.
- 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.
- free β human chorionic gonadotrophin - beta-hCG subunit of hCG used as a diagnostic marker for: early detection of pregnancy, Trisomy 21, spontaneous abortion, ectopic pregnancy, hydatidiform mole or choriocarcinoma.
- multiples of the median - (MoM) A multiple of the median is a measure of how far an individual test result deviates from the median and is used to report the results of medical screening tests, particularly where the results of the individual tests are highly variable.
- negative predictive value - The probability that a congenital anomaly is absent given that the prenatal screening test is negative.
- Non-Invasive Prenatal Testing - (NIPT) could refer to ultrasound or other imaging techniques, but more frequently used to describe analysis of cell-free fetal DNA circulating in maternal blood.
- polar body biopsy - (PB biopsy) An ART preimplantation genetic diagnosis technique that removes either the first or second polar body from the zygote. As these are generated by oocyte meiosis they detects chromosomal abnormalities only on the female genetics.
- positive predictive value - The probability that a congenital anomaly is present given that the prenatal screening test is positive.
- pre-implantation genetic diagnosis - (PGD, pre-implantation genetic screening) a diagnostic procedure for embryos produced through Assisted Reproductive Technology (ART, 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.
- single nucleotide polymorphisms - (SNPs) the variation in a single DNA nucleotide that occurs at a specific position in the genome.
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Cite this page: Hill, M.A. (2019, January 17) Embryology Amniocentesis. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Amniocentesis
- © Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G