Ureteral stenting can be a negative predictor for successful outcome following shock wave lithotripsy in patients with ureteral stones

PURPOSE To evaluate ureteral stenting as a negative predictive factor influencing ureteral stone clearance and to estimate the probability of one-session success in shock wave lithotripsy (SWL) patients with a ureteral stone. MATERIALS AND METHODS We retrospectively reviewed the medical records of 1,651 patients who underwent their first SWL. Among these patients, 680 had a ureteral stone measuring 4-20 mm and were thus eligible for our study. The 57 patients who underwent ureteral stenting during SWL were identified. Maximal stone length (MSL), mean stone density (MSD), skin-to-stone distance (SSD), and stone heterogeneity index (SHI) were determined by pre-SWL noncontrast computed tomography. RESULTS After propensity score matching, 399 patients were extracted from the total patient cohort. There were no significant differences between stenting and stentless groups after matching, except for a higher one-session success rate in the stentless group (78.6% vs. 49.1%, p=0.026). In multivariate analysis, shorter MSL, lower MSD, higher SHI, and absence of a stent were positive predictors for one-session success in patients who underwent SWL. Using cutoff values of MSL and MSD obtained from receiver operator curve analysis, in patients with a lower MSD (≤784 HU), the success rate was lower in those with a stent (61.1%) than in those without (83.5%) (p=0.001). However, in patients with a higher MSL (>10 mm), the success rate was lower in those with a stent (23.6%) than in those without (52.2%) (p=0.002). CONCLUSIONS Ureteral stenting during SWL was a negative predictor of one-session success in patients with a ureteral stone.