Accuracy of abnormal karyotypes after the analysis of both short- and long-term culture of chorionic villi.

We report in detail the cytogenetic results of 1838 consecutive chorionic villus samples with the availability of both short-term culture (STC-villi) and long-term culture (LTC-villi) preparations in 1561 cases (84.9%). A high degree of laboratory success (99.5%) and diagnostic accuracy (99.8%) was observed; in four cases of low mosaicism, all four associated with the final birth of a normal child, a small risk of uncertainty was accepted. The combined analysis of STC- and LTC-villi reduced follow-up amniocenteses by one-third in comparison with the analysis of STC-villi alone. We believe that the desired level of quality and accuracy of prenatal cytogenetics in chorionic villi can only be achieved when both STC- and LTC-villi are available. We conclude that CVS might then be the mode of prenatal diagnosis of first choice in pregnancies with a high (cytogenetic) risk. Copyright 2000 John Wiley & Sons, Ltd.