This prospective clinical study aims to evaluate preoperative, intraoperative, and postoperative characteristics of patients undergoing retrograde intrarenal surgery (RIRS) for urinary stone disease. A total of approximately 250 patients will be assessed to identify clinical, laboratory, and operative factors associated with postoperative fever and sepsis. By systematically collecting and analyzing perioperative data, the study seeks to determine independent predictors that may support improved risk stratification and patient safety in endourological practice.