Ureteral Wall Thickness At The Stone Site As An Indicator Of Ureteral Stone Impaction

Objective: To evaluate the ability of predicting ureteral stone impaction using ureteral wall thickness(UWT)and explore the relationship between UWT and URSL endoscopic findings and surgical results.Method: Collected the imformation of the patients who were diagnosed of ureteral stones and performed URSL during January 2015 to January 2017 retrospectively,including the patient's basic situation,stone-related information,URSL observations during surgery and follow-up related indicators.Measured the thickness of the ureteral wall at the stone site as well.Then evaluating the prediction power of UWT on stone impaction and obtaining the best cut-off value from ROC curve.The prediction of ureteral wall thickness on intraoperative endoscopic findings and postoperative results were explored through the cut-off value grouping.Results: Of the136 patients,48 were diagnosed with impacted stones.The univariate analysis showed the difference in ESWL history,degree of hydronephrosis,maximum stone diameter,and UWT between the impaction group and the non-impaction group.Multivariate analysis showed that the maximum stone diameter(OR=1.324,P=0.003)and UWT(OR=13.789,P<0.001)were independent factors to predict the stone impaction.The cut-off value obtained from the ROC curve is 3.55 mm,and the prediction accuracy is 0.869.The AUC of the maximum stone diameter is 0.717.Comparing the ROC curves of UWT and the maximum diameter of stones,UWT's predictive efficiency for impacted stones was significantly stronger than the maximum diameter of stones(P=0.009).What's more,The UWT were grouped according to the cut-off value.Compared with the low UWT group,in the high UWT group,the operation time was significantly prolonged(45min Vs 33.5min,P=0.001),the possibility of edema(48.3% Vs 16.7%,P<0.001)and stone fixation(37.9% Vs 16.7%,P=0.005)appeared during the operation was greater,the difficulty of the operation was increased,the stone-free rate(70.7% Vs 93.6%,P=0.039)was lower as well.Conclusion: The results of the study indicate that the thickness of the ureteral wall can be used as an important indicator for predicting ureteral stone impaction and the adverse conditions occurred during the surgery.It plays an important role in making surgical decision for patients to reduce complications and improve stone-free rate.