The impact of anesthesia type on Retrograde Intrarenal Surgery (RIRS) outcomes remains a subject of ongoing debate. Several studies have compared general anesthesia (GA) and spinal anesthesia (SA) in endourological procedures, with conflicting results regarding operative time, complication rates, and stone-free outcomes. Importantly, the interaction between anesthesia type and stone characteristics-particularly stone size-has not been fully elucidated. Therefore, this study aims to conduct a retrospective comparative analysis of general versus spinal anesthesia in patients undergoing RIRS at Qena University Hospital, with particular emphasis on the effect of stone size stratification on perioperative outcomes.

Urolithiasis is a common urological condition with a rising global incidence and prevalence, largely attributed to lifestyle, dietary factors, and metabolic disorders. The lifetime risk of developing urinary stones is estimated to be approximately 10-15%, with a high recurrence rate that imposes a significant burden on healthcare systems. Advances in minimally invasive techniques have revolutionized the management of renal calculi, with retrograde intrarenal surgery (RIRS) emerging as a safe and effective modality for treating renal stones of varying sizes and locations.

RIRS, performed using flexible ureteroscopy and laser lithotripsy, has gained widespread acceptance due to its minimally invasive nature, reduced morbidity, and favorable stone-free rates. It is particularly advantageous for managing stones less than 2 cm, although its indications have expanded to include larger and more complex stones in selected cases. Despite these advantages, several factors influence the success and safety of RIRS, including stone size, location, density, surgeon experience, and perioperative management strategies.

Among perioperative factors, the choice of anesthesia plays a critical role in determining surgical conditions and patient outcomes. General anesthesia (GA) is traditionally preferred for RIRS as it provides optimal airway control, complete immobility, and controlled ventilation, thereby facilitating precise endoscopic manipulation. In contrast, spinal anesthesia (SA) has been proposed as an alternative due to its advantages such as reduced postoperative pain, lower incidence of nausea and vomiting, and avoidance of airway-related complications. However, concerns remain regarding its limitations, including patient movement, inadequate control of respiration, and hemodynamic instability.

By evaluating stone-free rates and perioperative complications across different stone size categories, this study seeks to provide evidence-based guidance for optimizing anesthesia selection in RIRS.

Inclusion Criteria:

• Adult patients (≥18 years) scheduled for elective RIRS for renal stones <2 cm.
• Written informed consent obtained.

Exclusion Criteria:

• History of previous ureteral surgery or known ureteral stricture.
• Multiple or bilateral renal stones requiring staged procedures.

All eligible patients undergoing retrograde intrarenal surgery (RIRS)