Radiology, Vol 188, 165-169, Copyright © 1993 by Radiological Society of North America
Elevated levels of amniotic fluid alpha-fetoprotein: sonographic evaluation
M Robbin, RA Filly, S Fell, RB Goldstein, PW Callen, JD Goldberg and MS Golbus
Department of Radiology, University of California, San Francisco 94143- 0628.
From 1978 to 1990, 263 fetuses with an elevated level of amniotic fluid
alpha-fetoprotein (AF-AFP) (> 2.0 multiples of the median) were examined
with targeted fetal sonography. All cases of AF-AFP elevation among 22,355
genetic amniocenteses were represented. Sonography correctly showed 32 open
neural-tube defects, including 20 myelomeningoceles, and depicted 94% (63
of 67) of the anomalous fetuses. Two of five anomalous fetuses with normal
sonograms, however, had extremely high AF-AFP levels leading to
prospectively correct diagnoses of congenital nephrosis. Therefore,
programmatically, 97% (65 of 67) of the anomalous fetuses were recognized.
The three programmatic misdiagnoses were all detected in the neonatal
period and surgically corrected; subsequent development was normal. The
combination of an elevated AF-AFP level and a detailed sonogram allowed
distinction between a normal and an anomalous fetus in 99% of cases. When
elevated levels are noted, AF-AFP analysis followed by detailed sonography
is highly successful for the detection and characterization of anomalous
fetuses and the recognition of normal fetuses with physiologic increases of
this protein in the amniotic fluid.
