COMPARISON OF AMNIOTIC-FLUID AND MATERNAL SERUM ALPHA-FETOPROTEIN LEVELS IN THE EARLY ANTENATAL DIAGNOSIS OF SPINA BIFIDA AND ANENCEPHALY

Abstract

Amniotic-fluid alpha-fetoprotein (A.F.P.) levels were raised in early pregnancy in association with anencephaly and "open" spina bifida. Closed lesions, including encephalocele and hydrocephalus, were associated with normal levels as was an "open" spina bifida at 33 weeks of gestation. Radioimmunoassay of maternal serum-A.F.P. gave results in the normal range in eight of nine cases of neural-tube malformations tested, including anencephalics and open spina bifidas. In only one case, in which an anencephalic fetus was spontaneously aborted, was the serum level unequivocally raised. It is concluded that when ultrasound and amniocentesis are used most fetuses with anencephaly and open spina bifida are detectable before 20 weeks of gestation allowing selective abortion of most cases with neurological involvement when there is a history of previous affected fetuses. Closed lesions will usually be missed, and maternal serum-A.F.P. assay cannot be relied upon to detect neural-tube malformations in early pregnancy, whether open or closed.