Absence of urethral post-void milking: an additional cause for incontinence after radical prostatectomy?

Urinary incontinence following radical prostatectomy is thought to be mainly due to stress leak as a result of sphincter insufficiency or detrusor dysfunction. However, a number of patients complain of stress-independent urinary leakage following voiding, i. e. a post-micturition dribble, of uncertain origin. In order to establish wether post-micturition dribble is related to altered post-void milking in the urethra, voiding cystourethrograms (VCUGs) were performed before and after radical prostatectomy and correlated with the presence of post-micturition dribble.

23 VCUGs were recorded before and 19 VCUGs at 10-15 days following radical prostatectomy. A standard questionnaire regarding urinary symptoms was given to all patients pre- and postoperatively at defined intervals.

12 of 19 patients (63%) had post-void urethral milking prior to surgery, none of these reported post-micturition dribble. 6 of the 7 patients (86%) without post-void urethral milking reported post-micturition dribble. Postoperatively only 1 of 16 patients (6%) had post-void urethral milking. Of the 15 patients without postoperative urethral milking, 13 (87%) reported post-micturition dribble. The decrease in rate of milking and increase in rate of post-micturition dribble from before to after surgery was statistically significant (chi(2) test, p = 0.0001 and p<0.0001, respectively.

These data suggest that post-void milk-out of the urethra is often absent in the early postoperative period after radical prostatectomy and that this is associated with post-micturition dribble. Aside from detrusor and sphincter dysfunction, urethral dysfunction, i.e. the absence of urethral post-void milking, seems to be an additional cause of incontinence following radical prostatectomy.