Stone size matters: Volume versus diameter in predicting spontaneous passage of ureteral stones<10mm

International guidelines use maximum diameter to predict spontaneous passage of ureteral stones<10mm. This study compares its performance with calculated volume, a potentially more informative three-dimensional parameter.

Monocentric retrospective study including 121 patients admitted for renal colic. Maximum diameter and volume (calculated by ellipsoid formula and 3D segmentation) were evaluated against spontaneous passage at 4-6 weeks. Diagnostic performance of morphological parameters was evaluated by receiver operating characteristic (ROC) analysis. Multivariable logistic regression was used to identified factors independently associated with spontaneous passage.

Maximum diameter (AUC: 0.82; optimal threshold 5.35mm) proved significantly superior to volume for predicting spontaneous passage, with an overall passage rate of 77.7% in the cohort. In multivariate analysis, diameter≤5.35mm (OR=6.84) and distal location (OR=3.12) were the only independent predictive factors. Volumetric parameters provided no significant improvement.

Maximum diameter remains the best predictor of spontaneous passage for ureteral stones <10mm. Systematic integration of volume measurement in routine clinical practice appears unjustified.

Level III : Retrospective Cohort.