Late first-trimester invasive prenatal diagnosis: Results of an international randomized trial

J. Philip, R. K. Silver, R. D. Wilson, E. A. Thom, J. M. Zachary, P. Mohide, M. J. Mahoney, J. L. Simpson, L. D. Platt, E. Pergament, D. Hershey, K. Filkins, A. Johnson, L. P. Shulman, J. Bang, S. MacGregor, J. R. Smith, D. Shaw, R. J. Wapner, Laird G. Jackson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


OBJECTIVE: To assess, in a randomized trial, the safety and accuracy of amniocentesis and transabdominal chorionic villus sampling (CVS) performed at 11-14 weeks of gestation, given that this time frame is increasingly relevant to early trisomy screening. METHODS: We compared amnioceatesis with CVS from 77 to 104 days of gestation in a randomized trial in a predominantly advanced maternal age population. Before randomization, the feasibility of both procedures was confirmed by ultrasonography, and experienced operators performed sampling under ultrasound guidance; conventional cytogenetic analysis was employed. The primary outcome measure was a composite of fetal loss plus pre-term delivery before 28 weeks of gestation in cytogenetically normal pregnancies. RESULTS: We randomized 3,775 women into 2 groups (1,914 to CVS; 1,861 to amniocentesis), which were comparable at baseline. More than 99.6% had the assigned procedure, and 99.9% were followed through delivery. In contrast to previous thinking, in the cytogenetically normal cohort (n = 3,698), no difference in primary study outcome was observed: 2.1% (95% confidence interval 1.5, 2.8) for CVS and 2.3% (95% confidence interval, 1.7, 3.1) for amniocentesis. However, spontaneous losses before 20 weeks and procedure-related, indicated terminations combined were increased in the amniocentesis group (P = .07, relative risk 1.74). We found a 4-fold increase in the rate of talipes equinovarus after amniocentesis (P = .02) overall and in week 13 (P = .03, relative risk = 4.65), but data were insufficient to determine this risk in week 14. CONCLUSION: Amniocentesis at 13 weeks carries a significantly increased risk of talipes equinovarus compared with CVS and also suggests an increase in early, unintended pregnancy loss.

Original languageEnglish (US)
Pages (from-to)1164-1173
Number of pages10
JournalObstetrics and gynecology
Issue number6
StatePublished - Jun 2004

ASJC Scopus subject areas

  • Obstetrics and Gynecology

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