[Alpha-1-fetoprotein screening--development and problems]

Principle and logistic of alpha-1-fetoprotein (AFP-) screening is explained. It is estimated that approximately 2% of women pregnant for 16 to 18 weeks have elevated circulating AFP. By again measuring serum-AFP and by ultrasound examination such abnormal values can be explained by multiple pregnancies, wrongly estimated duration of pregnancy, abortus, etc, in approximately half of the cases. In 0.8 to 1% of all pregnant women the high-serum-AFP remains unexplained and an amniocentesis is indicated. An elevated amniotic AFP (0.1 to 0.2% of all pregnant women) strongly points to a fetus with an open neural tube defect. By also measuring amniotic acetylcholinesterase, this diagnosis can be distinguished from other fetal abnormalities associated with high amniotic AFP, such as omphalocele.