Spina bifida and neural tube defects

Case history

A pregnant Hispanic woman, whose body mass index is >35, is noted to have an elevated serum alpha-fetoprotein on routine triple screen. Consequently, an antenatal ultrasound is performed at 18 weeks' gestation, and fetal lumbar-level spina bifida is detected. The ultrasound reveals no evidence of hydrocephalus or cardiac, renal, or limb abnormalities. Amniocentesis shows a normal chromosome complement. Family history is negative for neural tube defects, and antenatal vitamins were taken as prescribed.