Comparison of Ureteral Stone Volume and Maximum Stone Length in Predicting Shock Wave Lithotripsy Success

This study aimed to compare maximum stone length and stone volume as predictors of stone-free (SF) status after extracorporeal shock wave lithotripsy (SWL) for ureteral stones.

Data from 236 patients treated with SWL for solitary radiopaque ureteral stone (5-15 mm) between January 2022 and March 2024 were retrospectively analysed. Stone length and volume were measured on noncontrast computed tomography. SF status was determined on radiography and ultrasonography 4 weeks after the last SWL session and defined as no residual stone or < 4 mm residual fragments. Binary logistic regression models were used to evaluate potential predictors of SWL outcome in univariable and multivariable analyses.

The overall SF rate was 68%. The non-SF group had significantly higher body mass index (BMI), Hounsfield unit, maximum stone length, stone volume, skin-to-stone distance and proximal ureteral diameter (all p < 0.05) compared with the SF group. Multivariate analysis revealed maximum stone length (p = 0.004) and BMI (p = 0.009) as independent predictors of SWL outcome, whilst stone volume lost statistical significance (p = 0.2).

Simple linear stone measurement without routine reliance on computed tomography (CT)-based volumetric assessment appears sufficient for predicting SWL outcomes in ureteral stones. This approach may help avoid the time-consuming nature and potential radiation exposure associated with volumetric analysis. Further prospective, multicentre studies with standardised imaging and large patient cohorts are warranted to confirm these results.