Primary Resection with Bladder Preservation for Colovesical Fistula: Clinical Outcomes and the Prognostic Significance of Perineural Invasion

Abstract Background: This study evaluated the safety and efficacy of primary resection and anastomosis (PRA) for colovesical fistula (CVF) of diverse etiologies and identified independent prognostic factors for oncological outcomes. Methods: We retrospectively analyzed 112 CVF patients (2017-2024) undergoing PRA with or without a defunctioning stoma, comparing clinical outcomes across benign and malignant cohorts. Results: Benign etiologies accounted for 33.0% (n=37) (colonic diverticulitis (n=19, 51.4%), Crohn's disease (n=14, 37.8%), and iatrogenic injury (n=4, 10.8%)), all underwent PRA with partial cystectomy, achieving zero mortality and no recurrence. Malignancies (67.0%) primarily included colorectal adenocarcinoma (sigmoid colon cancer (n=44, 58.7%) or rectal cancer (n=31, 41.3%)). Within the malignant cohort, radical cystectomy (n=15) was strictly necessitated by advanced disease features, including distal tumor location and extensive bladder wall invasion (80.0% vs 36.7%, P=0.003). Consequently, this advanced cohort experienced longer operative times (589 vs. 289 min), higher blood loss (600 vs. 100 mL), increased morbidity (80.0% vs. 20.0%, P<0.001), and shorter disease-free survival (DFS) (8 vs. 20 months, P=0.008) compared to those amenable to partial cystectomy (n=60). Crucially, multivariate analysis identified perineural invasion (PNI) (HR: 3.83, 95% CI: 1.49-9.84; P=0.005) as a critical independent predictor of recurrence, reflecting the impact of tumor biology over surgical extent. Conclusions: PRA is a definitive and versatile strategy for CVF. In malignant cases, bladder-preserving strategies are oncologically viable when R0 margins are achievable. Integration of PNI status and neoadjuvant therapy was essential for refining personalized multidisciplinary management.