Fetal pseudoascites.

A sonolucent band (pseudoascites) was retrospectively identified beneath the fetal abdominal wall in 39.7% of 141 normal obstetrical sonograms. In 12.6% of the examinations, the band was wide enough to be potentially confused with actual ascites. Pseudoascites was unrelated to fetal age or position, placental location, or equipment used. It was not reliably present on sequential examinations. The origin of this artifact remains unclear.