Criteria for the prenatal diagnosis of classic bladder exstrophy

Objective: To define ultrasonographic criteria for the prenatal diagnosis of classic bladder exstrophy. Methods: Forty-three prenatal ultrasound scans were studied from 25 pregnancies in which live delivery of an infant with classic bladder exstrophy occurred. The diagnosis of bladder exstrophy could be made retrospectively in 29 prenatal studies from 17 pregnancies. The time of the fetal ultrasound varied from 14-36 weeks' gestation (mean 23). The diagnosis of bladder exstrophy was made before delivery in only three cases. Results: Five factors associated with bladder exstrophy were identified: 1) The bladder was not visualized on ultrasound in 12 of 17 cases (71%); 2) a lower abdominal bulge representing the exstrophied bladder was seen in eight of 17 cases (47%); 3) a small penis with anteriorly displaced scrotum was identified in eight of 14 males (57%); 4) the umbilical insertion was low set in five of 17 cases (29%); and 5) abnormal widening of the iliac crests was seen in three of 17 cases (18%). Conclusion: The prenatal diagnosis of bladder exstrophy should be considered any time the bladder is not visualized or any of the aforementioned factors are noted.