The pathophysiology of post-radical prostatectomy incontinence: a clinical and video urodynamic study

PURPOSE: We examine various mechanisms of post-radical prostatectomy incontinence. MATERIALS AND METHODS: A total of 83 consecutive men (mean age 68 +/- 6.6 years) referred for evaluation of persistent post-radical prostatectomy incontinence were enrolled in the study. All patients underwent clinical and urodynamic evaluation. Final diagnosis was based on clinical judgment considering patient history, pad test, voiding diary, free (unintubated) uroflow measurements, video urodynamics and linear passive urethral resistance relation curves. We compared free uroflow and pressure flow obtained with a 7Fr urethral catheter in place, and empirically defined low urethral compliance as at least 10 ml. per second difference between these measurements. RESULTS: Sphincteric incontinence was the most common urodynamic finding, occurring in 73 patients (88%). Detrusor instability was identified in 28 patients (33.7%) and in 6 (7.2%) was the main cause of incontinence. In 2 other patients bladder outlet obstruction (1.2%) or impaired detrusor contractility (1.2%) was the only urodynamic finding. Impaired detrusor contractility was diagnosed by linear passive urethral resistance relation in 82% of cases but considered to be clinically relevant in only a third. In 25 cases (30.1%) low urethral compliance was noted, which we consider nearly synonymous with urethral scarring. CONCLUSIONS: Sphincteric incontinence is the most common urodynamic finding in patients with post-radical prostatectomy incontinence, although other findings may coexist. The most accurate diagnosis is attained when all objective measures are put in perspective with the clinical setting.