Functional and urodynamic characteristics of an ileal neobladder.

We examined the urodynamic characteristics and symptoms of 28 patients who had undergone the Stanford pouch bladder substitution following cystoprostatectomy. Urodynamics were obtained a mean of 18 months (range 6 to 43) after construction of the neobladder. Mean cystometric capacity was 699 cc (range 366 to 1,370). All patients voided by the Valsalva maneuver and achieved good peak flow rates (mean 19 cc per second). Of the patients 23 emptied to near completion with a mean post-void residual of 34 cc, while 5 had post-void residuals of greater than 150 cc (mean 630 cc). The neobladders demonstrated good compliance for the storage of urine, with a mean basal pressure of less than 15 cm. water at volumes of less than 500 cc at which most bladders function, and of 22.4 cm. water (range 1 to 72) at 100% capacity. Phasic neobladder contractions were present during filling cystometrography. While the number increased at higher neobladder volumes, the mean length and mean pressure did not. The mean pressure of contractions was less than 40 cm. water at lower and higher volumes. Daytime continence was attained in 26 of 28 patients (93%), while 17 (61%) attained nighttime continence. Of these 17 patients 14 (82%) had to void at least once at night to stay dry. Daytime incontinent patients had decreased neobladder compliance at high volumes compared to daytime continent patients (p < 0.05) but there was no difference in the maximal urethral closure pressure or the pressure of phasic contractions between these 2 groups. No difference was found in any urodynamic parameter between nighttime continent and incontinent patients. Patients with poor emptying ability (defined as a post-void residual of more than 150 cc) had increased neobladder compliance relative to patients with good emptying ability, as well as a statistically significant increased capacity (1,067 cc versus 623 cc). There was no difference in any important urodynamic parameter between patients who had and had not received postoperative chemotherapy. We conclude that a neobladder constructed from detubularized ileum achieves adequate capacity at low pressures with a satisfactory continence rate. Most patients empty the bladder to completion by Valsalva's maneuver. Low compliance at high volumes appears to be a factor in daytime incontinence.