Risks associated with an elevated amniotic fluid alpha-fetoprotein level.

Two and two-tenths percent of 85,000 consecutive amniotic fluid (AF) samples had alpha-fetoprotein (AFP) levels greater than or equal to 2.0 MoM. Half measured 2.0-2.4 MoM, and 93% had a normal outcome. Sixty-seven percent of those with higher levels had abnormalities. A positive acetylcholinesterase (AChE) increased the risk from 67% for levels between 2.0 and 2.4 MoM to 99% at greater than or equal to 5.0 MoMs. After a normal ultrasound and chromosome studies, the risk for a fetal abnormality was 1% for AF AFP measuring 2.0-2.4 MoM and 3% for higher levels.