Risk factors for obturator nerve reflex during bipolar transurethral resection of lateral bladder wall tumors

Obturator nerve reflex (ONR) remains a relevant intraoperative challenge during transurethral resection (TUR) of lateral wall bladder tumors (LWBT), even with bipolar technology. Identifying patients at increased risk may improve surgical safety and decision-making.

We retrospectively analyzed 737 patients who underwent bipolar TUR between July 2019 and October 2025. Patients with LWBT were grouped according to the intraoperative occurrence of ONR. Demographic, tumor-related, and perioperative variables were compared. ROC analyses and multivariable logistic regression analysis were performed.

Three hundred and four patients with LWBT were included, and ONR occurred in 36 cases (11.8%). Patients with ONR had significantly larger tumor size (50 vs. 25 mm, P = .006). In multivariable analysis, increasing LWBT size (OR:1.02, P = .041) and older age (OR:1.04, P = .048) were independently associated with ONR. ROC analysis demonstrated a modest predictive ability for tumor size (AUC = 0.643) and age (AUC = 0.614). A tumor size of approximately 30 mm and age ≥65 years provided clinically relevant thresholds for ONR risk. Overall complication rates, bleeding-related outcomes, and bladder perforation rates were similar between groups, although catheterization duration was longer in patients with ONR.

Despite bipolar technology, ONR occurs in a meaningful proportion of patients undergoing LWBT resection. Larger tumor size and advanced age were independently associated with ONR risk, although their discriminatory ability was modest. These parameters may provide supportive information for preoperative risk assessment and help guide individualized consideration of preventive strategies.