Risks of midtrimester amniocentesis; assessment in 3000 pregnancies.

The obstetric outcome of 3000 pregnancies with midtrimester amniocentesis was followed in all but one patient. Thirty pregnancies ended in fetal death or abortion within 3 weeks after amniocentesis. Chronologically 23 of these occurred in the first series of 1500 pregnancies and the remaining seven fetal deaths/abortions within 3 weeks after amniocentesis occurred in the second series of 1500 pregnancies. Fetal loss within 3 weeks after amniocentesis was apparently related to the experience of the obstetrician and to the use of modern ultrasound guidance. It is concluded that the risk of fetal death after midtrimester amniocentesis is approximately 0.5%, if only experienced obstetricians using modern techniques are involved.