Study of Factors Affecting Ureteral Access Sheath Insertion in Retrograde Intrarenal Surgery.

INTRODUCTION: Urolithiasis is a common urological disorder with a high recurrence rate and increasing global burden. Retrograde intrarenal surgery (RIRS) is an established minimally invasive treatment for renal and upper ureteric calculi. The ureteral access sheath (UAS) facilitates repeated access, improves irrigation, reduces intrarenal pressure, and enhances procedural efficiency. However, successful UAS insertion remains technically challenging and may influence surgical outcomes. The present study aimed to evaluate demographic, anthropometric, anatomical, and stone-related predictors of successful UAS insertion during RIRS. MATERIALS AND METHODS: This prospective observational study included 120 patients undergoing RIRS for renal or upper ureteric calculi. Demographic, clinical, radiological, and intraoperative variables were analyzed, and patients were categorized into successful and failed UAS insertion groups. Variables assessed included age, gender, body mass index (BMI), stone characteristics, hydronephrosis, ureteric orifice morphology, and computed tomography (CT)-measured common iliac artery diameter. Statistical analysis was performed using the Chi-squared test and the independent t-test. RESULTS: Successful UAS insertion was achieved in 104 (86.7%) patients, while failure occurred in 16 (13.3%). Age and gender were not significantly associated with UAS insertion outcome (p > 0.05). Patients with failed insertion had significantly higher body weight and BMI (p < 0.001). Obesity (BMI ≥ 30 kg/m²) was strongly associated with insertion failure (χ² = 47.96, p < 0.0001). All failed insertions occurred in patients with round-shaped ureteric orifices, whereas tent-shaped ureteric orifices were observed exclusively in the successful insertion group (p < 0.001). The mean CT-measured common iliac artery diameter was significantly greater in failed cases (p < 0.001). Stone characteristics and hydronephrosis were not significant predictors. CONCLUSION: Successful UAS insertion during RIRS is predominantly influenced by anthropometric and anatomical factors rather than stone-related variables. Higher BMI, round-shaped ureteric orifice morphology, and increased CT-measured common iliac artery diameter are important predictors of failed UAS insertion and may aid in preoperative risk assessment and surgical planning.