Chorionic villus sampling: experience of the first 1000 cases.

Chorionic villus sampling has become widely accepted as a first-trimester alternative to amniocentesis for the prenatal detection of genetic disorders. Our experience with 1000 consecutive cases suggests that spontaneous abortion following the procedure is related to the gestational age at which it is performed, and the rate is acceptably low (3.8%) when the procedure is performed from the ninth through the eleventh menstrual week. Later complications include chorioamnionitis (0.6%) and delayed rupture of membranes and/or oligohydramnios (0.8%). A discrepancy between the villus karyotype and that of the fetus was found in 1.7% of cases and most commonly consisted of mosaicism in the villus sample for a chromosomal abnormality that was not found in fetal samples. We conclude that although chorionic villus sampling appears to be an acceptably safe and reliable procedure, further investigation is needed before this first-trimester technique is widely utilized as an alternative to amniocentesis.