How good is ultrasound in the detection and evaluation of anterior abdominal wall defects?

The ability of routine obstetric ultrasound to detect and accurately describe fetuses with anterior abdominal wall defects has been examined in an unselected population using data from a regional abnormality survey. Examination between 16 and 22 weeks gestation detected 60% of defects with a false positive rate of 5.3%. Fetuses with gastroschisis were incorrectly assigned as exomphalos in 14.7% of cases recognized before 22 weeks gestation. The diagnosis, including description of associated detectable anomalies, was completely accurate in 71.6% of cases. Some of the problems of diagnostic accuracy need to be considered when counselling couples with a fetal anomaly. Cross-referral between obstetric ultrasound units should be encouraged to improve diagnostic accuracy. These results form the basis for audit of obstetric ultrasound in the diagnosis of fetal abnormality within a geographically defined population.