Duplicate bladder exstrophy: a new variant of clinical and embryological significance.

A case of duplicate exstrophy of a nature not previously encountered is reported, which we believe has important clinical and embryological implications. The patient presented with what appeared to be classical exstrophy. The inability to identify the ureteral orifices at operation led to the discovery of a previously unrecognized subjacent bladder of normal size and configuration except for a patulous bladder neck and associated epispadias. On excision of the duplicate bladder plate a coloniform projection was discovered that was lined with colonic mucosa. The surgical and potential embryological significance of this rare entity is described.