Voiding dysfunction in ileal neobladder.

PURPOSE: We attempt to understand better the voiding mechanism and determine the causes of voiding dysfunction in ileal neobladder patients. MATERIALS AND METHODS: The voiding condition in 12 bladder cancer patients who had undergone neobladder construction after radical cystectomy was examined by pressure-flow study and voiding cystourethrography. The patients were classified into 2 groups based on the maximum flow rate in a pressure-flow study: fine voiders (6), with a maximum flow rate of 15 ml. per second or more, and poor voiders (4), with a maximum flow rate of less than 15 ml. per second. RESULTS: Maximum flow rate in the fine voiders was 26.2 +/- 8.7 ml. per second (mean plus or minus standard deviation) compared with 9.4 +/- 0.9 ml. per second in the poor voiders. The fine voiders strained 1.5 +/- 0.9 times to void 100 ml. of urine, whereas the poor voiders strained 7.0 +/- 6.3 times. The bladder capacity, vesical opening pressure and vesical pressure at the maximum flow rate were similar in both groups. Pelvic floor electrical activity was amplified when the neobladder was either full or close to its capacity, and it was relaxed in coordination with abdominal straining in all patients. Voiding cystourethrography revealed that, in fine voiders, the neobladder outlet was funnel-shaped when the bladder was full and opened wider when the patient strained to void. However, in poor voiders, the neobladder outlet did not funnel even on abdominal straining. CONCLUSIONS: Neobladder patients void by abdominal straining and relaxing the pelvic floor musculature. To obtain smooth voiding in such patients, it is crucial to locate the neobladder opening at the most caudal portion and preserve neobladder outlet elasticity.