ELEVATED LEVELS OF AMNIOTIC-FLUID ALPHA-FETOPROTEIN - SONOGRAPHIC EVALUATION

From 1978 to 1990, 263 fetuses with an elevated level of amniotic flui d alpha-fetoprotein (AF-AFP) (>2.0 multiples of the median) were exami ned with targeted fetal sonography. All cases of AF-AFP elevation amon g 22,355 genetic amniocenteses were represented. Sonography correctly showed 32 open neural-tube defects, including 20 myelomeningoceles, an d depicted 94% (63 of 67) of the anomalous fetuses. Two of five anomal ous fetuses with normal sonograms, however, had extremely high AF-AFP levels leading to prospectively correct diagnoses of congenital nephro sis. Therefore, programmatically, 97% (65 of 67) of the anomalous fetu ses were recognized. The three programmatic misdiagnoses were all dete cted in the neonatal period and surgically corrected; subsequent devel opment was normal. The combination of an elevated AF-AFP level and a d etailed sonogram allowed distinction between a normal and an anomalous fetus in 99% of cases. When elevated levels are noted, AF-AFP analysi s followed by detailed sonography is highly successful for the detecti on and characterization of anomalous fetuses and the recognition of no rmal fetuses with physiologic increases of this protein in the amnioti c fluid.