Open neural tube defects: immunocytochemical demonstration of neuroepithelial cells in amniotic fluid.

Cytologic evaluation of second trimester amniotic fluid (AF) is a rapid, inexpensive adjunct to prenatal diagnosis of open neural tube defects (ONTDs). Our goal was to determine whether the neural-appearing cells and/or large foamy macrophages in the AF of anencephalics are indeed of neural and/or glial origin. In two second trimester patients with elevated serum alpha-fetoprotein (AFP) and polyhydramnios, fetal sonogram studies showed anencephaly; amniocentesis was performed for AF-AFP, cytogenetic, and cytologic studies.