Prevalence and predictors of postoperative detrusor underactivity after robot-assisted radical prostatectomy: A prospective observational study.

OBJECTIVES To identify the prevalence and predictors of postoperative detrusor underactivity during the early postoperative period after robot-assisted radical prostatectomy. METHODS We carried out a prospective observational study of 64 patients scheduled for robot-assisted radical prostatectomy using urodynamic study before and 1 month after robot-assisted radical prostatectomy. Detrusor underactivity was defined as maximum flow rate ≤15 mL/s and detrusor pressure at maximum flow rate ≤25 cmH2 O during voiding. Incidences of pre- and postoperative detrusor underactivity were assessed, and predictors of postoperative detrusor underactivity were determined using uni- and multivariate logistic regression analyses. Factors comprised patient characteristics (age, prostate weight etc.), operative factors (surgical duration, nerve sparing etc.) and preoperative urodynamic study parameters (maximum flow rate, bladder contractile index etc.). RESULTS Pre- and postoperative detrusor underactivity at 1 month after robot-assisted radical prostatectomy were detected in one patient (1.6%) and 24 patients (37.5%), respectively. Univariate analysis selected preoperative maximum flow rate (P = 0.02), detrusor pressure at maximum flow rate (P = 0.04) and bladder contractile index (P < 0.01) as predictors of postoperative detrusor underactivity (odds ratio 0.83, 0.97 and 0.94, respectively). On multivariate analyses, only preoperative bladder contractile index was associated with postoperative detrusor underactivity (P < 0.01; odds ratio 0.94). A cut-off of 102.8 offered optimal accuracy in receiver operating characteristic analysis. Patient characteristics and operative factors were not significantly associated with postoperative detrusor underactivity. CONCLUSIONS A comparatively high prevalence of postoperative detrusor underactivity is observed in patients at 1 month after robot-assisted radical prostatectomy. Patients with preoperative low bladder contractile index have a higher probability of developing early postoperative detrusor underactivity after robot-assisted radical prostatectomy.