Disorders of the bladder and cloacal anomaly.

The incidence of congenital urachal, bladder, and cloacal anomalies is low. Urachal remnants are the result of failure or delay in obliteration of the allantois. Exstrophy of the bladder or cloaca can be diagnosed on prenatal ultrasonography and represent a deviation from the normal embryologic sequence. Persistent cloaca is an anomaly occurring in girls, in which a common cavity exists into which the intestinal, urinary, and reproductive tracts all open. It is also often diagnosed on prenatal imaging.