Life without amniocentesis: elevated maternal serum alpha-fetoprotein in the Manitoba program 1986-91

Pregnant women demonstrating an elevated maternal serum alpha-fetoprotein level are at increased risk for fetal neural tube defect or other anomaly. Diagnostic procedures to evaluate these pregnancies include high-resolution ultrasound and amniocentesis to measure amniotic fluid levels of alpha-fetoprotein and N-acetylcholinesterase. We wished to examine the efficacy of detailed ultrasound examination alone, in evaluation of women with 'unexplained' elevation of maternal serum alpha-fetoprotein. The results showed that no neural tube defects were missed in the assessment of 1325 pregnancies with a raised level of maternal serum alpha-fetoprotein over 6 years, despite complete reliance on ultrasound in 98%. Detailed fetal ultrasound evaluation by experienced personnel is adequate to identify all cases of neural tube defects in a selected high-risk population.