Alphafetoprotein (AFP), concanavalin A non-reactive AFP and specific acetylcholinesterase in amniotic fluid from pathological pregnancies. Predictive values for open spina bifida.

Alphafetoprotein (AFP) and concanavalin A non-reactive alphafetoprotein determination and the acetylcholinesterase (AchE) qualitative test have been performed on amniotic fluid samples from 33 normal pregnancies, 44 pregnancies with fetal malformations and 8 normal pregnancies with elevated amniotic fluid alphafetoprotein (3 false positive AFP results, 5 contaminations with fetal blood). The validities of these three tests in detecting abnormal pregnancies are compared. The usefulness of the existing complementary tests in the detection of neural tube defects in a low neural tube defect incidence area is discussed. Risk figures for open spina bifida according to the prior risk situation and the results of maternal serum AFP, amniotic fluid AFP, AchE qualitative test and ultrasound examination have been calculated.