[Cause for increased alpha-fetoprotein values in amniotic fluid in prenatal diagnosis of genetic defects (author's transl)].

Alpha-fetoprotein measurement was undertaken in 1,582 instances, with 957 tests being applied to 776 patients for prenatal diagnosis of genetic defects, against the background of various indications - increased alpha-fetoprotein levels were recorded from the amniotic fluid of 24 patients (3.1 per cent). Values were defined as being increased, when they had exceeded threefold standard deviation from normal mean values. The causes underlying increased alpha-fetoprotein levels included six cases of anencephalia, one case of Turner's syndrome, one omphalocele, one intra-uterine foetal death, and one puncturing injury to a foetus. No foetal malformation or other foetal disorder, known to be accompanied by increased alpha-fetoprotein values, was recordable from 14 patients. Displacement of the pathological limit value to data five times the standard deviation reduced the number of erroneously positive findings to 0.8 per cent. Possibilities are discussed for differential of increased alpha-fetoprotein values. The proposal is made to respond to increased alpha-fetoprotein levels by another intensive ultrasonic B-scan test, control puncture, and, in certain cases, amniofetography.