Ureteral Wall Thickness as a Preoperative Indicator of Impacted Stones in Patients With Ureteral Stones Undergoing Ureteroscopic Lithotripsy


      To evaluate the clinical significance of ureteral wall thickness (UWT) to predict the presence of impacted stones in patients with ureteral stones undergoing ureteroscopic lithotripsy (URSL).

      Materials and Methods

      We retrospectively analyzed 130 procedures in patients with ureteral stones who underwent URSL between January 2014 and September 2016. Maximum UWT at the stone site was measured from computed tomography images. Clinical predictors of impacted stones were assessed using univariate and multivariate logistic regression analyses. Receiver operating characteristic curve analysis was applied to determine the UWT cutoff value and to evaluate its accuracy in predicting impacted stones. Moreover, we evaluated the association between UWT and endoscopic findings, as well as surgical outcomes.


      Of the 130 procedures, 50 (38.5%) involved patients with impacted stones. The univariate analysis showed significant differences in age, hydronephrosis, stone location, stone burden, and UWT in patients with and without impacted stones, and the multivariate analysis showed that age, stones in the middle ureter, and UWT (odds ratio 5.43, P < .001) were independent predictors of impacted stones. The receiver operating characteristic analysis showed that 3.49 mm was the optimal cutoff value for UWT, with a predictive accuracy of 0.87. High UWTs were associated with the presence of ureteral edema, polyps, white lesions, stone fixation, longer operation time, and lower endoscopic stone-free rate, compared with low UWTs (P < .05 each).


      High UWT is associated not only with a higher risk of impacted stones but also with poor endoscopic findings and adverse surgical outcomes in patients with ureteral stones undergoing URSL.
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      • Reply by the Authors
        UrologyVol. 108
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          Thank you for your insightful comments on our manuscript. We agree that not all patients with impacted stones have a high ureteral wall thickness (UWT) on non-contrast computed tomography (NCCT); the area under the curve for UWT is <0.90. Although we found that UWT was a strong predictor of the presence of ureteral stone impaction, the mechanism of the UWT findings on NCCT has yet to be elucidated. Our data indicate that a high UWT is correlated with ureteral inflammatory findings, such as ureteral edema, polyps, white lesions suspicious of ischemic mucosa, and stone fixation (P <.05 for all).
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      • Re: Yoshida et al.: Ureteral Wall Thickness as a Preoperative Indicator of Impacted Stones in Patients With Ureteral Stones Undergoing Ureteroscopic Lithotripsy (Urology 2017;106:45-49)
        UrologyVol. 108
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          We congratulate the authors for performing a unique study to evaluate the clinical significance of ureteral wall thickness (UWT) to predict the presence of impaction in patients undergoing ureteroscopic lithotripsy (URSL) for ureteric calculus. The authors showed that using a cutoff of 3.9 mm, the chances of impaction increased as the ureteral wall thickness increased. UWT measurement on preoperative non-contrast computed tomography (NCCT) was shown to be good parameter in the future to predict the presence of impacted stones and adverse surgical outcomes.
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