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

Obstet Gynecol. 2004 Jun;103(6):1164-73. doi: 10.1097/01.AOG.0000128049.73556.fb.

Abstract

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 amniocentesis 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 preterm 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.

Level of evidence: I

Publication types

  • Clinical Trial
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Abortion, Induced
  • Abortion, Spontaneous / epidemiology
  • Amniocentesis*
  • Chorionic Villi Sampling*
  • Clubfoot / epidemiology
  • Female
  • Fetal Death / epidemiology
  • Fetal Growth Retardation / epidemiology
  • Follow-Up Studies
  • Humans
  • Maternal Age
  • Obstetric Labor, Premature / epidemiology
  • Oligohydramnios / epidemiology
  • Pregnancy
  • Pregnancy Outcome / epidemiology*
  • Pregnancy Trimester, First
  • Pregnancy, High-Risk
  • Safety
  • Time Factors
  • Trisomy
  • Ultrasonography, Prenatal