Urinary retention is a problematic complication of robot-assisted radical prostatectomy (RARP). This adverse effect can occasionally develop and lead to a reduction in quality of life, increased medical costs, and so on. However, the pathophysiology remains unclear, and there are no predictive factors for postoperative urinary retention. Moreover, it is unknown whether postoperative urinary retention is related to postoperative lower urinary tract symptoms (LUTS) in the long term. The aim of this study was to investigate the factors contributing to urinary retention after RARP as well as the impact of urinary retention on postoperative LUTS.

This was a retrospective, single-center study. We assessed 963 patients who had undergone RARP for prostate cancer between May 2010 and January 2020 at our institution. RARP was carried out via the transperitoneal approach with six ports. Postoperative urinary retention was defined as urinary retention developing within 3 days after removal of the urethral catheter. We evaluated the relationships between postoperative urinary retention and the following factors: age, body mass index, prostate volume, preoperative international prostate symptom score (IPSS), intraoperative hemorrhage, nerve-sparing surgery, lymph node dissection, vesicourethral anastomosis methods (barbed suture or no-barbed suture), and the time of urethral catheter removal. Furthermore, we evaluated the difference in postoperative IPSS 12 months after surgery between patients with and without urinary retention.

The urethral catheter was removed, on average, 5.4±1.5 days after RARP. Of the 963 patients, 33 (3.4%) developed urinary retention after RARP. All 33 patients were treated with a temporal indwelling urethral catheter or intermittent self-catheterization. Only 3 patients developed anastomotic strictures subsequently. Univariate analysis showed that preoperative IPSS question 1 (incomplete emptying) and nerve-sparing surgery were significantly associated with urinary retention after RARP (p=0.02 and 0.04, respectively). Multivariate analysis also showed that these factors were significantly associated with urinary retention after RARP (incomplete emptying: odds ratio [OR], 1.34; p=0.03; 95% confidence interval [CI], 1.03–1.75; nerve-sparing surgery: OR 0.24; p=0.02; 95%CI, 0.07–0.81) (Table 1). Furthermore, multivariate analysis showed that preoperative IPSS question 5 (weak stream; OR, 1.63; p<0.001; 95% CI, 1.35–1.96) and postoperative urinary retention (OR, 3.24; p=0.03; 95% CI, 1.10–9.52) were significantly associated with postoperative IPSS question 5 (Table 2). In contrast, postoperative urinary retention was not significantly associated with other postoperative IPSS domains.

Our study indicates that (1) post RARP surgery, urinary retention is associated with the preoperative sensation of incomplete emptying and nerve-sparing surgery and (2) postoperative urinary retention leads to the postoperative sensation of weak stream 12 months after the RARP surgery. Since postoperative urinary retention was not associated with prostate volume in this study, preoperative detrusor underactivity may be one of the underlying mechanisms of postoperative urinary retention. In addition, moderate anastomotic stricture may occur after urinary retention as these patients in this study experience postoperative sensation of a weak stream. It is possible that nerve-sparing surgery could prevent postoperative urinary retention and the following anastomotic stricture via preservation of urethral blood supply. Further studies are required to confirm this.

Postoperative urinary retention is associated with preoperative sensation of incomplete emptying and nerve-sparing surgery. Since patients with postoperative urinary retention could have LUTS in the long term, they require careful follow-up.