Amniography in the prenatal diagnosis of neural tube defects.

Amniography for the visualization and confirmation of suspected neural tube defect was performed in 9 midtrimester gravidas. In all cases, amniotic fluid alpha-feto protein (AFP) was abnormally elevated. Four cases of anencephaly and one of spina bifida were demonstrated by amniography. These pregnancies were terminated and the defects were confirmed by gross pathologic examination. In 4 remaining cases, amniography was normal. Three of these pregnancies proceeded to term, culminating in the birth of a normal child. The fourth patient had spontaneous abortion of a normal fetus at 23 weeks of gestation. The experience reported here suggests that amniography is an important adjunctive diagnostic technique in the prenatal diagnosis of neural tube defect, and if used correctly, may significantly reduce the chance of false-positive diagnosis.