Effect of Preoperative Hydronephrosis on Ureteral Stenosis after Flexible Ureteroscopy: A Propensity Scores Matching Analysis

Abstract OBJECTIVES: Ureteral stenosis is a serious complication after flexible ureteroscopy. Other studies have confirmed that stone impaction and intraoperative ureteral injury are important factors causing stricture, and how to predict the occurrence of stricture before surgery may be an important topic. This study retrospectively studied the influence of preoperative hydronephrosis degree on ureteral stenosis after flexible ureteroscopy to explore whether preoperative hydronephrosis degree could predict postoperative ureteral stenosis. METHODS: A retrospective study was conducted on patients who received flexible ureteroscopy in our hospital for upper ureteral calculi from January 2015 to June 2018. The postoperative follow-up was performed for 36 months, and intraoperative and postoperative complications were recorded. According to the degree of hydronephrosis, the patients were divided into mild hydronephrosis group and moderate and severe hydronephrosis group. Preoperative clinical baseline data of the patients were adjusted by propensity matching score, and differences in intraoperative mucosal injury, operative time, incidence of postoperative ureteral stricture, and SFR 1 month after surgery were statistically analyzed. Kaplan-Meier method and Log-rank test were used to compare the differences in the cumulative incidence of ureteral stenosis between the two groups. Cox regression analysis was used to compare the hazard ratio of ureteral stenosis between the two groups. RESULTS: A total of 447 patients with 469 sides surgery were included, including 349 sides in the mild hydronephrosis group and 120 sides in the moderate and severe hydronephrosis group. 30 sides in 29 patients developed ureteral stenosis. The stenosis rate before propensity matching analysis was 6.4%, and 8% after propensity matching analysis. However, the SFR and operation time were not statistically consistent. Kaplan-Meier showed a significant difference in the cumulative incidence of ureteral stenosis between the two groups.CONCLUSIONS: Preoperative patients with moderate to severe hydronephrosis are more likely to have intraoperative mucosal injury, and the incidence of ureteral stricture is higher after flexible ureteroscopy. Preoperative hydronephrosis is an important predictor of ureteral stricture. Preoperative hydronephrosis is an important predictor of ureteral stricture.