Four years' cytogenetic experience with the culture of chorionic villi

In 1958 chorionic villus samples, investigated by culture method, we found 137 (7%) abnormalities. The abnormal results were classified in certain abn ormal (generalised abnormal at high probability) and uncertain abnormal (po tentially confined to the placenta) results. Certain abnormal were 73 cases (3.7%). Uncertain abnormal were 64 cases (3.3%), in which confirmation stu dies were done in 47 cases. In 12 cases of these 47, the abnormality was co nfirmed and in 35 cases (1.8%) the abnormality was confined to the placenta . Among the latter cases, poor pregnancy outcome [16% intrauterine death (I UD), 6% intrauterine growth retardation (IUGR)] was increased. Total maternal cell contamination was not seen. The positive predictive value of all confirmed abnormal cases was 66%. The positive predictive value was 100%, for indications 'ultrasound abnormaliti es' and 'carrier' and between 50 and 60% for all other indications. Predict ive value among uncertain abnormal cases was low (26%). However, the positi ve predictive value depends of the type of abnormality. Therefore we conclude that the culture method for chorionic villi is a good test for indications 'ultrasound abnormalities' and 'carrier' and reliable for all other indications. Whether or not follow-up investigations should be offered to the parents depends of the type of abnormality. We conclude t hat the culture method is reliable for prenatal diagnosis and can be used a s the sole investigative method. Copyright (C) 2000 John Wiley & Sons, Ltd.