Prenatal hydronephrosis revealing a bladder diverticulum.

Bladder diverticula can be either congenital or acquired. They are the formation of a urothelial hernia through the muscle wall fibers of the bladder. Congenital bladder diverticula are rare and there are no previous reports showing them to have been found through an antenatal ultrasound exam revealing the presence of hydronephrosis.