Introduction

Radical prostatectomy (RP) damages the anatomical and functional structure of bladder and consequently induces postoperative not only urinary incontinence but also impaired detrusor contractility. The reported prevalence of detrusor underactivity (DU) after retropubic RP (RRP) ranges from 25% to 34%, but the incidence and predictive factors of de novo DU after RRP has remained unknown. This prospective study compares urodynamic parameters and detrusor function in patients before and one month after undergoing robot-assisted RP (RARP) and determines the prevalence and predictive factors of de novo DU arising in patients during the early postoperative period after RARP.

Methods

Urodynamic parameters were compared before and one month after RARP in 63 patients (mean age, 66.8 ± 4.7 years). DU was defined as a maximum flow rate (Qmax) of ≤ 15 mL/s and detrusor pressure at Qmax (PdetQmax) ≤ 25 cmH₂0 during attempted voiding. The incidence of pre- and post-operative DU was initially assessed and then predictive factors of postoperative DU were determined using univariate and multivariate logistic regression analyses. The factors comprised patient characteristics (age, body mass index, prostate volume, etc.), operative factors (surgical duration, estimated blood loss, nerve-sparing, etc.) and pre-operative urodynamic study (UDS) parameters (maximum bladder capacity, bladder compliance, detrusor overactivity, Qmax, PdetQmax, bladder contractile index (BCI), etc.).

Results

Preoperative and postoperative DU at one month after RARP were detected in one (1.6%) and 24 (37.5%) patients, respectively. Univariate analysis selected preoperative Qmax (p = 0.02), PdetQmax (p = 0.04) and BCI (p < 0.01) as predictors of postoperative DU (univariate odds ratios; 0.83, 0.97 and 0.94, respectively). Multivariate analyses of factors identified as significant in univariate analyses associated only preoperative BCI with postoperative DU (p < 0.01; multivariate odds ratio: 0.94). A cutoff value of 101.3 offered the optimal accuracy in receiver operating characteristics analysis. Patient characteristics and operative factors were not significantly associated with postoperative DU in both univariate and multivariate analyses.

Conclusions

A comparatively high prevalence of de novo DU was observed in patients at 1 month after RARP bladder, which may have been due to bladder denervation during surgery. Preoperative BCI is the most important factor for predicting early postoperative DU after RARP.

Funding

none