The Role of Renal Pelvis Urine Attenuation Value in Forecasting Infection Risk After Mini-Percutaneous Nephrolithotomy

<b><i>Objective:</i></b> To evaluate whether renal pelvis urine density (RPUD), measured on preoperative computed tomography (CT), predicts infectious complications following percutaneous nephrolithotomy (PCNL). <b><i>Methods:</i></b> This retrospective study included patients who underwent PCNL between June 2019 and June 2024 at a tertiary care center. Patients with preoperative infection signs, drainage devices, or incomplete data were excluded. All included patients had sterile urine cultures preoperatively. RPUD was measured on noncontrast CT by two independent urologists, and interobserver agreement was calculated. Patients were grouped according to the presence of postoperative infectious complications (fever, sepsis, or septic shock). Demographic and perioperative variables were compared. Logistic regression was used to identify independent predictors of infection. <b><i>Results:</i></b> A total of 226 patients were analyzed. Patients with postoperative infections had significantly higher RPUD values (13.7 versus 6.0 Hounsfield units, <i>P</i> = .001) and longer operative times (70 versus 50 minutes, <i>P</i> = .001). On multivariate analysis, both RPUD (odds ratio: 1.238) and operative time (odds ratio: 1.055) were independent predictors. ROC analysis showed that an RPUD cutoff of 9.250 predicted infection with 80.0% sensitivity and 80.1% specificity (AUC: 0.875). Interobserver reliability for RPUD was excellent (intraclass correlation coefficient: 0.942). <b><i>Conclusions:</i></b> Preoperative RPUD is a reliable, noninvasive radiological marker for predicting infectious complications after PCNL. Routine measurement of RPUD may improve preoperative risk stratification and optimize perioperative management. These findings should be validated in future prospective, multicenter studies.