Ureteral wall volume at ureteral stone site is a critical predictor for shock wave lithotripsy outcomes: comparison with ureteral wall thickness and area.

Abstract

Our objectives were to compare measurements of ureteral wall area, ureteral wall volume and ureteral wall thickness for their use in prediction of shock wave lithotripsy outcomes. We retrospectively identified 218 patients that underwent shock wave lithotripsy for ureteral calculi with pretreatment non-contrast computed tomography. We measured ureteral wall thickness, ureteral wall area and ureteral wall volume by high functional viewer. Ureteral wall thickness was defined as the maximum thickness of ureteral wall, and ureteral wall area as the area of ureteral wall around the stone in the maximal stone diameter on axial computed tomography image. Ureteral wall volume was defined as the volume of ureteral wall from the upper to lower edge of the stone. Treatment success was defined as absence of residual fragments within 3months after the first session. We compared the outcome predictive power among these parameters and logistic regression analysis to identify factors contributing to treatment failure. The treatment success rate was 47.6%. Ureteral wall thickness, ureteral wall area and ureteral wall volume in successful cases were all significantly smaller than those in unsuccessful cases (all p < 0.01). Area under curve of ureteral wall volume was the largest of these parameters and significantly larger than that of ureteral wall thickness (p < 0.01). On multiple logistic regression analysis, ureteral wall volume was the only significant independent predictor of treatment outcome. Ureteral wall volume is a better predictor of shock wave lithotripsy outcome than ureteral wall thickness or ureteral wall area.