Fetal Blood Sampling

Introduction

See also Non-Invasive Prenatal Testing.

Some Recent Findings

Noninvasive Prenatal Testing: The Future Is Now "Prenatal detection of chromosome abnormalities has been offered for more than 40 years, first by amniocentesis in the early 1970s and additionally by chorionic villus sampling (CVS) in the early 1980s. ...The ability to isolate fetal cells and fetal DNA from maternal blood during pregnancy has opened up exciting opportunities for improved noninvasive prenatal testing (NIPT). Direct analysis of fetal cells from maternal circulation has been challenging given the scarcity of fetal cells in maternal blood (1:10,000-1:1,000,000) and the focus has shifted to the analysis of cell-free fetal DNA, which is found at a concentration almost 25 times higher than that available from nucleated blood cells extracted from a similar volume of whole maternal blood. There have now been numerous reports on the use of cell-free DNA (cfDNA) for NIPT for chromosomal aneuploidies-especially trisomy (an extra copy of a chromosome) or monosomy (a missing chromosome)-and a number of commercial products are already being marketed for this indication. This article reviews the various techniques being used to analyze cell-free DNA in the maternal circulation for the prenatal detection of chromosome abnormalities and the evidence in support of each."

More recent papers

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Cordocentesis

Percutaneous umbilical blood sampling (PUBS, fetal blood sampling, umbilical vein sampling) This chromosome analysis test is done at in the 18th week or later of high-risk pregnancies. The technique may be used when either alternative tests (amniocentesis, CVS, ultrasound) are either inconclusive or not achievable (severe oligohydramnios).

The risk of a miscarriage related to the test is about 3 per cent (occurring in 3 in 100 pregnancies).

References

Search PubMed

April 2010

• Fetal Blood Sampling - All (2020) Review (267) Free Full Text (196)

Search PubMed: Fetal Blood Sampling

Prenatal Diagnosis Terms

• 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 - (cfDNA) refers to fetal DNA circulating and isolated from the plasma portion of maternal blood. Can be performed from GA 10 weeks as a first-tier test or as a second-tier test, with women with increased probability on combined first trimester screening offered cfDNA or diagnostic testing.

• 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.

• quadruple test (maternal serum testing of a-fetoprotein Template:AFP, free B-hCG or total hCG, unconjugated estriol, and inhibin A) is a fetal chromosomal anomaly test usually carried out later in pregnancy (GA 14 to 20 weeks).

• single nucleotide polymorphisms - (SNPs) the variation in a single DNA nucleotide that occurs at a specific position in the genome.

• triple test - (maternal serum testing of a-fetoprotein Template:AFP, free B-hCG or total hCG, and unconjugated estriol) is a fetal chromosomal anomaly test usually carried out later in pregnancy (GA 14 to 20 weeks).

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Cite this page: Hill, M.A. (2023, December 2) Embryology Fetal Blood Sampling. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Fetal_Blood_Sampling

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© Dr Mark Hill 2023, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G