Ultrasound and amniotic fluid alpha-fetoprotein in the prenatal diagnosis of spina bifida.
Amniotic fluid alpha-fetoprotein (AFP) assays and detailed ultrasound examinations were performed in 376 prenatal patients at risk for a neural tube defect (high-risk group). In addition, 2436 patients who underwent amniocentesis for other indications underwent preamniocentesis ultrasound screening and amniotic fluid AFP assays (low-risk group). There were 10 neural tube defects in the high-risk group (7 open and 3 closed) and 3 in the low-risk group (all open). Two of the 3 closed defects were detected prenatally. The predictive value of an elevated AFP level for an abnormal fetus was much higher in the high-risk (6 of 6, 100%) than in the low-risk group (1 of 6, 17%). When both ultrasound and AFP assay results were normal, the chance of a normal outcome was very high in both the high- and low-risk groups (99.7 and 100%, respectively). It was of particular interest that in the low-risk group, the likelihood of an abnormal outcome in women with elevated AFP and a normal ultrasonogram was low (0 of 5).
D000649:Amniocentesis; D000653:Amniotic Fluid / Q000032:analysis*; D005260:Female; D005865:Gestational Age; D006801:Humans; D009436:Neural Tube Defects / Q000175:diagnosis; D011247:Pregnancy; D011296:Prenatal Diagnosis; D016136:Spina Bifida Occulta / Q000175:diagnosis*; D014463:Ultrasonography; D000509:alpha-Fetoproteins / Q000032:analysis*
D000509:alpha-Fetoproteins