The role of preoperative ureteral diameter measurements in predicting difficult access during retrograde ıntrarenal surgery: a retrospective analysis of 234 patients.

Retrograde intrarenal surgery (RIRS) is a minimally invasive procedure used for the management of renal and ureteral stones. However, successful placement of a ureteral access sheath (UAS) remains a critical challenge, particularly in patients with narrow ureters. Preoperative measurement of ureteral diameter via computed tomography (CT) may help predict access difficulties and optimize surgical planning. This study aimed to evaluate the role of preoperative ureteral diameter measurements (distal, iliac, and upper ureters) in predicting difficult UAS placement during RIRS. A retrospective analysis was conducted on 234 patients who underwent RIRS for kidney stones. Ureteral diameters were measured at three anatomical levels using preoperative CT. Patient demographics, stone size, operative time, and surgical outcomes were recorded. Difficult access was defined as unsuccessful initial UAS placement requiring additional interventions such as guidewire manipulation, balloon dilation, or selection of a smaller sheath. Patients with smaller ureteral diameters at all three measured levels had a significantly higher incidence of difficult UAS placement (p < 0.05). Multivariate analysis confirmed ureteral diameter as an independent predictor of difficult access. Additionally, previous stone-related interventions and patient demographics showed significant associations with ureteral diameter, further influencing surgical outcomes. Preoperative ureteral diameter measurement via CT provides valuable predictive insights into access challenges during RIRS. Routine assessment of ureteral diameter can enhance surgical planning, improve procedural efficiency, and reduce perioperative complications.