URSL Angle for Predicting Intraoperative Conversion

This international multicenter retrospective cohort study aims to externally validate the URSL Predictive Angle, a novel CT-derived morphometric parameter, as an imaging biomarker for predicting intraoperative conversion risk during transurethral ureteroscopic lithotripsy (URSL) for ureteral calculi. Intraoperative conversion is defined as the unanticipated abandonment of the planned endoscopic approach due to unfavorable ureteral anatomy or stone impaction, necessitating recourse to open ureterolithotomy, laparoscopic ureterolithotomy, or ureteral stent placement with planned staged secondary intervention. Such conversions are associated with protracted operative duration, heightened anesthetic exposure, and increased physical, psychological, and financial burdens on patients. The URSL Predictive Angle is a geometric parameter derived from preoperative coronal CT reformations that quantifies the degree of local ureteral angulation induced by an impacted calculus. Preliminary single-center data demonstrated robust predictive fidelity of this metric with an area under the ROC curve of 0.861 and an optimal discriminatory threshold of 131.8° yielding a sensitivity of 82% and a specificity of 88%. This study will enroll eligible patients from multiple domestic and international tertiary care hospitals who underwent URSL for ureteral calculi between January 1, 2018, and December 31, 2025. The primary outcome is intraoperative conversion of surgical approach. The predictive performance of the URSL angle will be evaluated using ROC curve analysis with AUC calculation. Propensity score matching and multivariable logistic regression will be employed to address potential confounding. This study is registered as a patient registry with a cohort model. Data collection is retrospective, involving abstraction from electronic medical records, operative logs, and PACS. A waiver of informed consent has been requested based on the retrospective design, minimal risk determination, stringent anonymization procedures, and impracticability of obtaining individual consent.

NCT Number	NCT07561684
Lead Sponsor	The First Hospital of Jilin University
Conditions	Ureteral Calculi
Enrollment	2,200 participants
Start Date	2026-06-01
Primary Completion	2026-08-01 (estimated)
Study Completion	2026-09-30 (estimated)
Updated on ClinicalTrials.gov	2026-05-01