Predictive CT-based parameters for successful medical expulsive therapy in unilateral ureteral calculi: A prospective observational study.

Introduction: Medical expulsive therapy (MET) has been shown to be a safe and effective option for the spontaneous passage of uncomplicated ureteric stones sizing ⩽10 mm in selected cases. However, there is lack of evidence on the predictors of successful MET. Our objective was to identify parameters that can accurately predict the spontaneous passage of ureteral stones during MET.

Methods: Patients receiving MET (Tamsulosin 0.4 mg once daily (OD)) for a single unilateral ureteral calculi sizing ⩽10 mm were followed after 1 month using Non contrast Computed tomography (NCCT). Various parameters such as stone-related parameters (location, density, volume and transverse, longitudinal, and sagittal diameters), ureter-related parameters (diameter, density, and wall thickness at the stone site) and grade of hydronephrosis were evaluated on CT images and analyzed by using univariate, multivariate and receiver operating characteristic (ROC) curve analyses.

Results: Of 55 patients, 31 (56.4%) passed the stone successfully within 4 weeks of MET. Univariate analysis revealed these patients tended to have lower ureteric stones (p-value- 0.048), lower longitudinal (p-value- 0.024) and transverse stone diameters (p-value- 0.006), lower stone volume (p-value- 0.015) and ureteral wall thickness (UWT; p-value- 0.001). In multivariate analysis, only UWT at the stone site (p 0.036) was a significant predictor of the successful passage of calculus. The UWT cut-off was 2.1 mm with sensitivity and specificity of 83.8% and 62.5%, respectively, with an Area Under Curve (AUC) of 0.7856.

Conclusion: The most significant predictor of successful stone passage in MET of unilateral ureteral stones was maximal UWT, with an optimal cut-off point of 2.1 mm.