Comparison of chorion villus sampling and early amniocentesis for karyotyping in 1,492 singleton pregnancies.
This was a prospective study in 1,492 women with singleton viable pregnancies undergoing chorion villus sampling (CVS) or early amniocentesis (EA) at 10-13 weeks of gestation because of advanced maternal age, parental anxiety or family history of chromosomal abnormality in the absence of parental chromosomal rearrangement. They were offered the option of having CVS or EA, or to be randomised into one of the two tests. CVS was performed in 652 cases (375 by choice and 277 by randomisation) and EA was performed in 840 cases (562 by choice and 278 by randomisation). Both procedures were carried out by transabdominal ultrasound-guided insertion of a needle (20 gauge) using a free-hand technique. The two techniques were similar in providing a sample (CVS 99.3%, EA 100%) and in giving a non-mosaic cytogenetic result (CVS 97.5%, EA 97.9%). Spontaneous loss (intrauterine or neonatal death) after EA (total group 4.9%, randomised subgroup 5.8%) was significantly higher than after CVS (total group 2.1%, randomised subgroup 1.8%; difference 2.8%, 95% CI 1.3-4.3%, and difference 4%, 95% CI 1.3-6.7%). The gestation at delivery and birth weight of the infants after EA and CVS were similar. In the EA group the incidence of talipes equinovarus (1.66%) was higher than in the CVS group (0.48%), but this difference was not significant.