Retrospective Analysis of the Factors Affecting Intraoperative and Immediate Postoperative Complications of Retrograde Intrarenal Surgery Classified by the Clavien and Satava Grading Systems.

Background: To classify intraoperative and postoperative complications using the modified Clavien classification system (MCCS) and modified Satava classification system (SCS) and to evaluate the parameters associated with complications in patients undergoing retrograde intrarenal surgery (RIRS) for renal and proximal ureteral stones. Materials and Methods: We performed a retrospective analysis of 949 patients who underwent RIRS for renal stones and proximal ureteral stones at two institutions between March 2015 and June 2020. Intraoperative complications were assessed using the SCS, and postoperative complications were graded according to the MCCS. Univariate and multivariate analyses were undertaken to determine predictive factors affecting complication rates. Results: The median stone size was determined as 13 mm (range 10-20 mm). The stone-free rate was 83.6% after the first intervention. Reprocedure was applied to 89 of the patients with residual stones and the final stone-free rate was 94.4% after reprocedure. According to SCS, the number of intraoperative events and complication incidences was 153 (16.1%). MCCS revealed postoperative complications in 121 (12.8%) patients. Major complications were observed in 18 (1.9%) patients. The rate of complications was higher in patients with renal anomalies (9.9% vs 3.4%, p = 0.001). Stone location, stone size, stone burden, stone number, stone density, and residual fragments were determined to be associated with the development of complications (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.002, and p < 0.001, respectively). In addition, the multivariate analysis revealed that only the presence of residual fragments was a significant predictor of complication development for the patients with Grade ≥3 complications according to MCCS (p = 0.032). However, significant predictors were stone burden (p < 0.001), stone density (p = 0.002), and fluoroscopy time (p < 0.001) for those with Grade ≥2b complications according to SCS. Conclusion: This study showed that abnormal kidney anatomy, operation time, stone burden, and residual fragments were reliable predictors of complication development during and after RIRS. Appropriate preoperative management should be planned according to these predictors to prevent intraoperative and postoperative complications.