Predictors of Urinary Leak after Urinary Reconstruction in Pelvic Exenteration and beyond Total Mesorectal Excision: A Retrospective Cohort Study

BACKGROUND: Extended pelvic resections requiring cystectomy or partial cystectomy, including pelvic exenterations and beyond total mesorectal excision (bTME) rectal cancer surgery, carry a substantial risk of urinary leak following urinary reconstruction. This study evaluated pre-operative predictors and postoperative indicators of urinary anastomotic leak. METHODS: All patients who underwent pelvic exenteration or bTME with ureteric reconstruction between 2015 and 2022 in a single centre were retrospectively analysed. Exclusions included palliative resections, complete ureteric resections, and cases with intraoperative ureteric injuries. The primary outcome was radiologically confirmed urinary leak within 30 days. Baseline and operative variables were compared, and postoperative drain and serum creatinine were analysed. RESULTS: Among 110 patients, 14 (12.7%) developed a urinary leak. Leak rates were 7.9% after ileal conduit diversion (7/89) and 33.3% after non-ileal conduit reconstruction (7/21) (p = 0.005). Obesity (BMI ≥ 30kg/m²) was associated with leak (OR 3.42, 95% CI 1.10-10.69; p = 0.045). Partial cystectomy was associated with the highest odds of leak (OR 19.38, 95% CI 2.90-213.37; p = 0.006). In the subset of patients sampled (6 leak, 46 non-leak), postoperative day 1 drain creatinine discriminated leaks (AUC 0.964, 95% CI 0.908-1.000). Urinary leak was associated with longer hospital stay (32 days vs 21 days; p = 0.045) and a higher rate of readmission (43% vs 11%; p = 0.01). CONCLUSION: BMI and partial cystectomy were associated with urinary leak after extended pelvic resections requiring ureteric reconstructions. Among patients with available measurements, POD-1 drain creatinine showed promising discrimination for early urinary leaks; however, because sampling was non-uniform, this finding requires prospective validation.