The predictive value of ureteral wall area for impacted ureteral stones

Objective: To investigate the clinical indicators for preoperative prediction of impacted ureteral stones and analyze the predictive value of ureteral wall area(UWA). Methods: A total of 197 patients who underwent ureteroscopic lithotripsy due to ureteral stones at our institution from January to December 2020 were retrospectively analyzed. Preoperative patient age, gender, body mass index (BMI), history of hypertension, diabetes mellitus, side of stone, location of stone, maximum diameter of stone, CT value of stone, C-reactive protein (CRP), creatinine, renal pelvis diameter, ureteral wall thickness and UWA were collected. Patients were divided into impacted and non-impacted groups according to whether the stones were impacted intraoperatively. Univariate analysis was used to compare the differences in each clinical indicator between the two groups, and multivariate logistic regression was performed to analyze the independent predictors of impacted stones for those with differences. The receiver operating characteristic (ROC) curve was used to analyze the predictive power of each independent predictor, and the Delong test was used to analyze whether the difference in the area under the curve (AUC) of each independent predictor was statistically significant. Results: All 197 patients successfully completed the operation, aged 51 (36, 56) years; 137 males and 60 females. According to the results of ureteroscopy, they were divided into 82 cases of impacted ureteral stones and 115 cases of non-impacted ureteral stones. Univariate analysis showed that there were significant differences in maximum stone diameter, stone CT value, renal pelvis diameter, ureteral wall thickness and ureteral wall area between the two groups (P 0.05). Multivariate logistic regression analysis showed that stone CT value (P<0.01), ureteral wall thickness (P<0.001) and ureteral wall area were independent predictors of impacted ureteral stones (P<0.001). The ROC curve was used to compare the predictive efficacy of independent predictors of stone CT value, ureteral wall thickness and ureteral wall area. The area under the ureteral wall area curve was the largest (AUC = 0.901, 95%CI: 0.859-0.943, P<0.001), followed by ureteral wall thickness (AUC = 0.799, 95%CI: 0.736-0.862, P<0.001) and stone CT value (AUC = 0.700, 95%CI: 0.626-0.775, P<0.001). By Delong test, there were significant differences in AUC between ureteral wall area and stone CT value (Z=4.527, P<0.001) and ureteral wall thickness (Z=3.407, P<0.001). The best predictive value of ureteral wall area was 79.6 mm2. The sensitivity and specificity of this critical value for predicting ureteral incarcerated calculi were 80.1% and 89.5%. Conclusions: The UWA, ureteral wall thickness as well as the CT value of stones were all independent predictors of impacted ureteral stones, and UWA had a better predictive value.