Randomized study of early amniocentesis versus chorionic villus sampling: a technical and cytogenetic comparison of 650 patients.

Abstract

In a prospective randomized trial of 650 patients at 10-13 weeks' gestation, early amniocentesis was compared to chorionic villus sampling (CVS) for successful sampling and cytogenetic results and the speed with which results can he obtained. The indications for fetal karyotyping were advanced maternal age, parental anxiety or a family history of chromosomal abnormality in the absence of a balanced parental translocation. At early amniocentesis, 10 ml of amniotic fluid were successfully obtained in all 324 cases, in 320 (98.8%) at the first attempt and in four cases (1.2%) after two needle insertions. CVS provided sufficient material for cytogenetic analysis in 314 of 326 (96.3%) cases at the first attempt and in nine (2.8%) after two needle insertions; in three cases only maternal tissue was obtained and subsequently early amniocentesis was performed. Cell culture and chromosomal analysis were successful in 318 of 324 (98.1%) cases of early amniocentesis and in 321 of the 323 (99.4%) cases of CVS where villi were obtained. The median interval between sampling and successful result from cell culture was 12 days for early amniocentesis and 11 days for CVS. Mosaicism was detected in five cases of CVS but in none of the early amniocenteses; three of these cases were confirmed as true fetal mosaics. This study illustrates that early amniocentesis is a viable alternative to CVS for first-trimester fetal karyotyping. The results of the continuing prospective 1 trial will establish the safety and cytogenetic accuracy of the two techniques.