Incontinence after augmentation cystoplasty and internal diversion.

The collective published experience with continent urinary diversions, together with our own, indicates that there are certain basic principles with regard to continence, which is dependent on: (1) the pressure generated by the reservoir; (2) the outflow resistance of the outlet; and (3) detubularization, which is crucial to diminish the uninhibited involuntary bowel contractions. Detubularized ileal pouches provide the lowest pressures (less than 20 cm H2O). Although the majority of patients (approximately 85%) who have a low-pressure ileal neobladder are completely continent, a few experience persistent nocturnal incontinence as a result of low resting urethral pressure. Numerous continence methods have been described, each with its own unique set of problems. The most physiologic continence mechanism is the external urethral sphincter in men. It is clear that total continence with this mechanism is not assured. Other factors such as reservoir contractions, overflow incontinence, decreased sphincter tone, and loss of the normal vesicourethral reflex play an important role in nocturnal incontinence. However, understanding these contributing elements will allow us to refine the construction of a continent physiologic bladder substitute.