Renal pelvis urine density as a predictor of infectious complications after semi-rigid ureterorenoscopy for ureteral stone treatment.

Introduction: This study aimed to investigate whether renal pelvis urine density (RPUD) serves as a reliable predictor of postoperative infectious complications in patients undergoing semi-rigid ureterorenoscopy (URS) for ureteral stone treatment.

Methods: We retrospectively reviewed 1104 patients who underwent semi-rigid URS for ureteral stones. Patients were divided into two groups based on whether they developed postoperative infections within one month (n=64) or not (n=1040). Demographic variables (age, sex, body mass index), comorbidities, stone characteristics (location, size, density), and operative parameters (operation time, stent/catheter placement) were recorded. Renal pelvis urine density was measured in Hounsfield units on preoperative imaging.

Results: Of the 1104 patients, 64 (5.8%) developed postoperative infections. The median RPUD was significantly higher in the infectious group (10 [5-17] HU) compared to the non-infectious group (4 [2-6] HU; p=0.001). On multivariate analysis, sex (odds ratio [OR] 4.001, 95% confidence interval [CI] 2.231-7.174, p=0.001), body mass index (OR 0.920, 95% CI 0.860-0.984, p=0.015), operation time (OR 0.963, 95% CI 0.932-0.996, p=0.028), and RPUD (OR 0.809, 95% CI 0.771-0.849, p=0.001) were independent predictors of postoperative infection. The area under the curve was 0.784 (p<0.001, 95% CI 0.711-0.857), demonstrating good discriminative ability. When a cutoff value of 6.35 was applied, the sensitivity and specificity were 71.9% and 76.9%, respectively, for predicting postoperative infections.

Conclusions: Higher RPUD is significantly associated with an increased risk of infectious complications following semi-rigid URS for ureteral stones. Incorporating RPUD into preoperative assessments may help identify high-risk patients and optimize perioperative management to reduce infection-related morbidity.