RANDOMIZED TRIAL COMPARING 1ST-TRIMESTER TRANSCERVICAL CHORIONIC VILLUS SAMPLING AND 2ND-TRIMESTER AMNIOCENTESIS

A total of 800 patients were randomized at the 9th to 11th week of pre gnancy either for transcervical chorionic villus sampling (CVS) on the day of trial entry or for amniocentesis (AC) at the 16th week. The in dication for fetal karyotyping was maternal age in 94 per cent of the cases; the mean maternal age was 39.2 years. An adequate sample was ob tained in 98.3 per cent of the cases in the CVS group and in all cases in the AC group. Retesting was indicated in 3.3 per cent of the CVS c ases. An abnormal karyotype was found in 6.1 per cent of the CV sample s and in 4.5 per cent of the amniotic fluid samples. There was one fal se-positive chromosome result in both groups. Twelve (3.1 per cent) mi scarriages occurred by the 22nd week of pregnancy in the CVS group in pregnancies intended to continue. No difference was seen between the g roups for total fetal loss rates. The number of surviving infants in t he CVS group was 92.2 per cent and in the AC group 91.7 per cent (rate difference 0.5 per cent (95 per cent confidence interval - 3.3 to 4.3 )). In our study, both the diagnostic accuracy and the risk of fetal l oss were equal in the CVS and AC groups.