Persistent urogenital sinus: prenatal diagnosis and pregnancy complications.

Prenatal diagnosis of fetal hydrocolpos caused by persistent urogenital sinus is described. The urethrovaginal communication allowed urine to empty from the bladder into the vagina, which subsequently dilated, causing bilateral hydronephrosis, distention of the fetal abdomen, decreased urinary output, oligohydramnios, and abdominal dystocia at delivery.