Faint and positive amniotic fluid acetylcholinesterase with a normal sonogram

Objective: Both faint and positive amniotic fluid acetylcholinesterase determinations have been associated with fetal abnormalities. We evaluated the effect of a normal sonogram and positive or faint acetylcholinesterase level on the risk for anomalies. Study Design: Between Jan. 1, 1989, and Feb. 1, 1995, 4859 amniocenteses were performed. Twenty-three cases of abnormal acetylcholinesterase determinations combined with normal sonograms were identified, and pregnancy outcomes were determined. Results: One abnormal karyotype was identified (45,X/47,XXX mosaic). No neural tube defects were seen in infants with an abnormal acetylcholinesterase determination and normal sonogram. One fetus of a twin pregnancy had a ventral wall defect that was not detected on ultrasonography. Seventy-three percent of infants were normal at birth, but 27% of the pregnancies had abnormal outcomes. Conclusions: Advances in ultrasonography have led to improved detection of fetal abnormalities. With a normal karyotype, repeat invasive testing may not be necessary.