Study of ureteral and renal morphometry on the outcome of ureterorenoscopic lithotripsy: The critical role of maximum ureteral wall thickness at the site of ureteral stone impaction

PURPOSE: The purpose is to study the association of stone, ureteral, and renal morphometric parameters with the relevant outcome variables, i.e., complication rate, stone-free rate (SFR), and operating time of ureterorenoscopic lithotripsy. Although a safe procedure, it still occasionally has major complications. Computed tomography (CT) scan is often performed to diagnose ureteral calculi, providing opportunities for ureteral morphometry that may have a bearing on the outcome of the procedure. MATERIALS AND METHODS: Ureteric, renal, and stone morphometric parameters were measured from CT of the abdomen and pelvis of the 110 patients with ureteral calculi who underwent ureteroscopic lithotripsy (URSL). Data were collected retrospectively in 25 patients and prospectively in 85 patients. Association of these parameters with the outcome variables of the procedure mentioned above was studied. RESULTS: On univariate analysis, body mass index, stone size, and maximum ureteral wall thickness (MUWT) were found to have a significant association with URSL complications, SFR, and duration of surgery. On multivariable analysis, only MUWT was found to be an independent risk factor for URSL complications. In 90% of total patients with residual stones, MUWT was found to be >4.8 mm. CONCLUSION: Ureteral wall thickness of >4.8 mm is associated with prolonged duration of surgery and lower SFR. Patients with ureteral wall thickness of >4.8 mm at the site of ureteral stone who are planned for URSL must be counseled about the higher chances of residual stones and the need for additional procedure.