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Evidence summaries

Amniocentesis and Chorionic Villus Sampling for Prenatal Diagnosis

Second trimester amniocentesis increases the risk of spontaneous miscarriage but is safer than transcervical chorionic villus sampling and early amniocentesis. Level of evidence: "A"

A Cochrane review [Abstract] 1 included 14 studies. In a low risk population with a background pregnancy loss of around 2%, a second trimester amniocentesis will increase this risk by another 1%..Spontaneous miscarriages are more common following second trimester amniocentesis as compared with controls with no amniocentesis (2.1% vs. 1.3%; RR 1.02-2.52). Early amniocentesis is not a safe early alternative to second trimester amniocentesis because of increased pregnancy loss (7.6% vs. 5.9%; RR 1.29, 95% CI 1.03 to 1.61) and higher incidence of talipes compared to CVS (chorionic villus sampling) (RR 6.43, 95% CI 1.68 to 24.64). Compared with second trimester amniocentesis, transcervical CVS carries a significantly higher risk of pregnancy loss (14.5% versus 11%; RR 1.40, 95% CI 1.09 to 1.81) and spontaneous miscarriage (12.9% versus 9.4%; RR 1.50, 95% CI 1.07 to 2.11). One study compared transabdominal CVS with second trimester amniocentesis and found no significant difference in the total pregnancy loss between the two procedures (6.3% versus 7%). Transcervical CVS is more technically demanding than transabdominal CVS with more failures to obtain sample and more multiple insertions.

A retrospective study 2 evaluated procedures of invasive prenatal testing (2001-2014) including 936 amniocentesis procedures and 1051 chorionic villus samplings, of which 405 cases were executed transabdominally and 646 transcervically. Only singleton pregnancies before 24 weeks and 0 days of gestation where the pregnancy outcome was known were included. The total fetal loss rates were determined to be 1.73% for transabdominal chorionic villus sampling, 2.01% for transcervical chorionic villus sampling and 1.18% for amniocentesis. No statistically noticeable differences between the total fetal loss rates of all three procedures were found (P=0.399).

    References

    • Alfirevic Z, Navaratnam K, Mujezinovic F. Amniocentesis and chorionic villus sampling for prenatal diagnosis. Cochrane Database Syst Rev 2017;(9):CD003252. [PubMed]
    • Niederstrasser SL, Hammer K, Möllers M et al. Fetal loss following invasive prenatal testing: a comparison of transabdominal chorionic villus sampling, transcervical chorionic villus sampling and amniocentesis. J Perinat Med 2017;45(2):193-198. [PubMed]

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