Factors associated with de novo overactive bladder following robot-assisted radical prostatectomy: impact of membranous urethral length and prostate volume

Abstract Objective This study assessed the occurrence of de novo overactive bladder (OAB) and identified factors of de novo OAB after robot-assisted radical prostatectomy (RARP). Methods A total of 227 patients who underwent RARP and had no preoperative diagnosis of OAB were retrospectively evaluated. De novo OAB was defined according to postoperative symptom assessment performed 12 months after surgery. Clinical variables, including membranous urethral length (MUL) and risk classification, were evaluated. Univariable and multivariable logistic regression analyses were conducted to identify factors associated with de novo OAB. Results De novo OAB developed in 39 patients (17.2%) 12 months after RARP. In the multivariable analysis, smaller prostate volume (odds ratio [OR] 1.09; P = 0.0008), preoperative nocturia ≥ 2 episodes per night (OR 3.41, P = 0.0066), and shorter postoperative MUL (OR 1.79; P < 0.0001) were identified as independent factors of de novo OAB. Among patients with shorter preoperative MUL, those with a postoperative MUL ≥ 14 mm had a significantly lower incidence of de novo OAB than those with a postoperative MUL < 14 mm (8.3% vs. 38.4%; P < 0.0001). Conclusions Smaller prostate volume, preoperative nocturia, and shorter postoperative MUL were significant factors of de novo OAB development. Maximal preservation of urethral length during surgery may reduce the risk of de novo OAB.