Bladder prolapse through a patent urachus: fetal and neonatal features.

We report a term male neonate who was born with a large, red, tubular, mucosa-lined umbilical mass containing a patent lumen. Prenatal ultrasonographic screening at 20 to 28 weeks of gestation revealed a large cyst at the umbilicus, communicating with the urinary bladder. The cyst resolved at 32 weeks, and a small solid mass was newly seen on the fetal abdominal wall, inferior to the umbilical cord insertion. At operation, the mass was discovered to be the prolapsed, open, everted dome of the urinary bladder. The dome was resected, and the bladder was repaired in 2 layers after identification of the ureteral orifices. Bladder prolapse through a patent urachus can be predicted by prenatal ultrasound and has a distinct neonatal appearance.