Safe or sorry?.

Chorion villus sampling (CVS), like amniocentesis, is a diagnostic test carried out in pregnancy to detect Downs' syndrome. Its advantage is that it can be carried out at 8 or 9 weeks' gestation instead of the 16 weeks required for amniocentesis. But a disturbing number of children born to women who had this test suffer from birth defects such as missing fingers, toes, or hands. There are also cases of children born without a respiratory passage or tongue. A survey of the world's experts in this field reveals that the earlier the test is carried out, the less risk there is of damage, but that there is widespread confusion over how late the test can be administered. Precision in administering the test is crucial; it is deceptively simple procedure for which sufficient training is not always given and a clumsy operator can inflict damage on the foetus. The programme calls for patients to be made aware of these factors before agreeing to the CVS test.