Megacystis microcolon intestinal hypoperistalsis syndrome: bladder distension and pyelectasis in the fetus without anatomic outflow obstruction.

We report a case of a 46,XY male infant with a history of normal amniotic fluid levels who was delivered by elective cesarean section at 38.5 weeks' gestation because of progressive bladder distension, hydroureteronephrosis, and what was thought to be a dilated posterior urethra. The child died at 19 days of age of cardiovascular complications. The autopsy revealed megacystis, bilateral megaureters and pyelocaliectasis, congenital absence of ganglion cells in the bladder wall, renal dysplasia, and a microcolon. No dilation or anatomic obstruction of the posterior urethra was found. These findings strongly suggest the diagnosis of megacystis microcolon intestinal hypoperistalsis syndrome. We discuss the ultrasound findings of in utero bladder distension with hydronephrosis and one of its rare etiologies.