Impact of maternal serum alpha-fetoprotein screening on antenatal diagnosis.

An analysis has been made of indications for amniocentesis in the Edinburgh area from 1979 to 1981. About 5% of all mothers underwent the procedure. Among 2137 amniocenteses, 37% were performed on mothers 35 years old or more, and 30% on patients with raised serum alpha-fetoprotein. The total number of amniocenteses and the categories have been stable for the past three years. As a result of amniocentesis 104 pregnancies were terminated, 66 of which (63%) followed a raised maternal serum alpha-fetoprotein indication, while only 10 (9.6%) were in mothers aged 35 or more. There were a further 12 terminations based on raised serum alpha-fetoprotein but where no amniocentesis had been thought necessary. Even when figures for anencephaly are excluded from the analysis, maternal serum alpha-fetoprotein screening was responsible for detecting 35 out of 63 (56%) abnormal fetuses. This constitutes a strong case for the continuation of alpha-fetoprotein screening programmes.