The impact of normalized energy utilization on clinical outcomes and complications in endourological stone surgery: a...

This prospective study evaluated the impact of normalized energy utilization on clinical outcomes and complications in endourological stone surgery. Between January 2024 and April 2025, 478 consecutive patients undergoing holmium: YAG laser lithotripsy were enrolled. Stone characteristics, energy parameters, operative outcomes, and complications were prospectively recorded. Normalized energy values (J/mm³) were calculated as total energy divided by stone volume. The primary endpoint was complication development. Mean normalized energy was 22.5 ± 13.1 J/mm³ (range: 5.8-72.4). High-density stones (> 1000 HU) and lower calyceal locations required significantly higher energy (p < 0.001 and p = 0.012, respectively). ROC analysis identified 25 J/mm³ as the optimal threshold for predicting complications (AUC = 0.792, sensitivity 75.8%, specificity 70.5%). Energy utilization above 25 J/mm³ increased complication risk 4.25-fold (95% CI: 2.05-8.82, p < 0.001), while energy above 30 J/mm³ significantly increased severe papillary damage risk (68.5% vs. 25.3%, p < 0.001). In multivariate analysis, normalized energy > 25 J/mm³ (OR: 4.25, p < 0.001), prolonged operative time (OR: 1.02, p = 0.018), and high stone density (OR: 2.54, p = 0.017) were independent risk factors for complications. Overall stone-free rate was 83.7%. This study establishes evidence-based energy thresholds for safe laser lithotripsy, demonstrating that normalized energy monitoring can guide surgical decision-making and reduce complications in endourological stone surgery.