Renal Pelvic Urine Density for Early Prediction of Post-Decompression Systemic Inflammatory Response in Stone-Related Obstruction

OBJECTIVE: This study was conducted to evaluate the prognostic value of renal pelvic urine density (RPUD) measured by computed tomography (CT) in predicting systemic inflammatory response syndrome (SIRS) after decompression in patients with non-infectious obstructive uropathy associated with stones. PATIENTS AND METHODS: Patients who underwent emergency decompression due to non-infectious obstructive uropathy caused by urinary stones between January 2018 and July 2025 were retrospectively analyzed. Cases with clinical, laboratory, or radiological findings of infection were excluded from the study. Demographic characteristics, stone characteristics, degree of hydronephrosis, RPUD, and perioperative parameters were recorded. Patients were divided into SIRS (+) and SIRS (-) groups on the basis of postoperative clinical findings. Independent predictors of SIRS were determined using multi-variable logistic regression, and the diagnostic performance of RPUD was evaluated using receiver operating characteristic (ROC) analysis. RESULTS: A total of 247 patients were included in the study, and 36 (14.6%) developed SIRS after decompression. RPUD values were significantly higher in SIRS (+) patients (12.5 vs. 9.4 HU, p < 0.001). Multi-variable analysis identified RPUD as an independent predictor of SIRS (odds ratios [OR] = 2.061, 95% CI: 1.586-2.679, p < 0.001). ROC analysis showed that an RPUD cutoff value of 10.5 HU predicted SIRS development with 77.8% sensitivity and 74.9% specificity, area under the curve (AUC) = 0.830. CONCLUSION: RPUD is a strong and independent prognostic marker for the early prediction of SIRS after decompression in non-infectious obstructive uropathy associated with stones.