Urodynamic evaluation of changes in urinary control after radical retropubic prostatectomy.

PURPOSE: Urodynamic evaluations were done in patients before and after radical prostatectomy to obtain more information about the factors that affect continence.
MATERIALS AND METHODS: Urodynamic testing was done in 82 patients before, and 6 to 8 weeks and 6 months (9 cases) after radical prostatectomy. Evaluation included measurement of cystometric bladder capacity, compliance, functional profile length, maximal urethral closure pressure, maximal urethral closure pressure during voluntary contraction of the external sphincter, residual urine, maximal flow rate and bladder instability.
RESULTS: The continence rate was 33.4, 69.4, 84.7 and 90.9% at 1, 3, 6 and 12 months after radical prostatectomy, respectively. Mean functional urethral length decreased from 61 mm. preoperatively to 25.9 mm. postoperatively, maximal urethral pressure from 89.6 to 65.2 cm. water and bladder capacity from 338.7 to 278.8 ml. Bladder instability was found in 17 and 41% of cases before and directly after radical prostatectomy, respectively. There was a statistically significant difference in maximal urethral closure pressure (68.1 versus 53.1 cm. water) as well as functional urethral length (27.6 versus 20.5 mm.) in continent versus incontinent patients, respectively. Urodynamic examination 6 months after prostatectomy showed an increase in functional profile length and maximal urethral pressure, while bladder measurements did not change significantly.
CONCLUSIONS: After radical prostatectomy significant changes in bladder and sphincter measurements are noted. Urethral closure pressure, functional urethral length and bladder stability are significant urodynamic factors that influence continence after radical prostatectomy.