Urinary Diversions And Neobladders

The urinary bladder, situated in the extraperitoneal space of the pelvis behind the pubis, is uniquely designed both to provide a low-pressure reservoir for urine storage during the filling phase and to efficiently empty completely during the micturition phase. The layered design of the bladder and its complex neural control allows the normal bladder to fill without involuntary contractions and to empty with a highly coordinated contraction of the detrusor muscled simultaneously with the relaxation of the urinary sphincter(s) to expel urine. Within the urinary system, the bladder is the most common site of malignancy. For localized muscle-invasive bladder cancers, and in select cases of non-muscle-invasive cancers, removal of the entire bladder with a radical cystectomy and creation of some type of urinary diversion is recommended as the gold standard. In certain other instances, such as refractory chronic bladder pain or where the bladder does not function properly (either due to injury, surgery, or radiation), the bladder can similarly be removed with the creation of urinary diversion. The methods for urinary diversion following cystectomy can be divided into the continent or incontinent diversions. In the continent diversions, urine is stored in a reservoir created by bowel segments prior to voluntarily emptying via volitional voiding or catheterization. In incontinent diversions, urine is diverted into an intestinal segment that is brought to the skin via an ostomy for continuous drainage into a collecting bag.