Predictors of spontaneous passage of ureteral calculi in cases receiving Medical Expulsive Therapy: A Prospective, Observational Study

Abstract

Abstract Introduction: Medical expulsive therapy (MET) is a safe and effective option for the spontaneous passage of uncomplicated ureteric stones sizing ≤ 10 mm. Our objective was to identify parameters that can accurately predict the spontaneous passage of ureteral stones during MET. Methods Patients receiving MET (tamsulosin 0.4mg od) for a single unilateral ureteral calculi sizing ≤ 10 mm were followed up to 1 month. The potential parameters, stone related (location, density, volume and transverse, longitudinal, sagittal diameters), ureter related (diameter, density, and wall thickness at the stone site) and hydronephrosis grade were evaluated on CT images and analyzed by using univariate, multivariate and receiver operating characteristic (ROC) curve analyses. Results Of fifty-five 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 0.048), lower longitudinal (p 0.024) and transverse stone diameters (p 0.006), lower stone volume (p 0.015) and ureteral wall thickness (p 0.001). In multivariate analysis, the only variable with significant independent predictive value on successful stone passage (SP) was the maximal ureteral wall thickness (UWT) at stone site (p 0.036). Sagittal stone diameter, ureteral diameter, ureteral & stone densities were found to be insignificant. The UWT cut off was 2.1mm with sensitivity and specificity of 83.8% and 62.5% respectively. Conclusion The most significant predictor of successful stone passage in MET of unilateral ureteral stones is the maximal UWT, with an optimal cut-off point of 2.1mm.