Urorectal septum malformation sequence.

The urorectal septum malformation sequence consists of absent perineal and anal openings in association with ambiguous genitalia and urogenital, colonic, and lumbosacral anomalies. The full sequence is highly lethal, and the partial sequence, characterized by a single perineal opening draining a common cloaca, is compatible with life. Defects in mesodermal proliferation early in embryogenesis result in this rare condition. Timely urologic and surgical evaluations and reconstructions are imperative and necessary for survival. Urologists should be familiar with the mechanisms and presentations of this condition, as they may be involved in the diagnosis and management of such patients.