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.

Urinary stone disease is a common global health problem with an increasing incidence and significant clinical and economic burden. Retrograde intrarenal surgery (RIRS) has become a widely accepted, minimally invasive, and effective treatment option for renal and proximal ureteral stones. Advances in flexible ureteroscope design, laser technologies, and endourological instrumentation have further improved the safety, efficiency, and applicability of RIRS. As a result, there has been a marked increase in the preference for RIRS among urologists in recent years.

Despite its advantages, RIRS is associated with complication rates reported between 9% and 25%. Postoperative fever and urinary tract infection are the most frequently observed complications and may progress to sepsis, which represents a potentially life-threatening condition in patients with urinary stone disease. These infectious events remain a concern even when appropriate antibiotic prophylaxis and aseptic surgical principles are applied. Identifying risk factors that may predict postoperative infection and sepsis is therefore essential for improving perioperative decision-making and patient safety.

Previous studies have suggested potential associations between operative characteristics, preoperative bacteriuria, patient-related comorbidities, and postoperative infectious outcomes; however, most available evidence originates from retrospective analyses with limited variables. There remains a need for prospective, systematically collected data evaluating a broad set of perioperative clinical and laboratory parameters to better define predictive factors.

This prospective patient registry study aims to evaluate comprehensive perioperative variables to identify predictors of postoperative urinary tract infection and sepsis following RIRS. Parameters to be assessed include operative time, stone burden, intraoperative irrigation characteristics, perioperative cultures, and a detailed panel of inflammatory biomarkers such as C-reactive protein, procalcitonin, albumin, fibrinogen, and D-dimer. The study will also record the onset, duration, and severity of postoperative fever, together with other clinical findings relevant to infectious complications. Through this structured approach, the study seeks to determine independent risk factors that may assist clinicians in predicting, preventing, and managing postoperative infection and sepsis in patients undergoing RIRS.

Inclusion Criteria:

• Age 18 years or older.
• Patients scheduled to undergo retrograde intrarenal surgery (RIRS) for the treatment of renal or ureteral stones.
• Completion of routine preoperative and postoperative clinical assessments required for RIRS.
• Ability to provide informed consent.

Exclusion Criteria:

• Terminal-stage malignancy.
• Bleeding diathesis or known immunodeficiency.
• Active infectious condition at the time of surgery.
• Patients deemed unsuitable for anesthesia or surgery by the Department of Anesthesiology.
• Pregnancy.
• Contraindications to RIRS or inability to complete required perioperative evaluations.

The study population consists of adult patients undergoing retrograde intrarenal surgery (RIRS) for the treatment of renal or ureteral stones at Erciyes University Hospital. All participants are evaluated using standard preoperative laboratory tests, imaging studies, and perioperative clinical assessments. Patients included in this registry represent a typical endourological population treated with RIRS in routine clinical practice. Individuals with active infections at the time of surgery, contraindications to surgery, or conditions preventing informed consent are excluded.