Complications of retrograde intrarenal surgery classified by the modified Clavien grading system.

The increase in the retrograde intrarenal surgery (RIRS) has been accompanied by the increase in complications. This study identified the factors that affected the severity of the complications using the modified Clavien classification system (MCCS). Three hundred and twenty-two consecutive RIRS performed by a single surgeon were analyzed. Data collection included demographics, clinical parameters, and perioperative and postoperative complications. The rate of adverse events for each of the Clavien grades was calculated, and statistical comparisons were made. The impact of each of the factors on the severity of the complications, based on the MCCS, was investigated using the univariate and multivariate analyses. The total complication rate was 26.1% (MCCS: I = 67.7%, II = 22.7%, IIIb = 7.2%, IVb = 2.4%). On the univariate analyses, the following factors affected complication: positive preoperative urine culture, operative time, irrigation rate, and stone burden. Multivariate logistic regression analysis demonstrated that positive preoperative urine culture, irrigation rate, and operative time were the significant factors affecting the complications. Most of the RIRS complications were in the lower Clavien grades and major complications were uncommon. Positive preoperative urine culture, irrigation rate, and operative time were the factors that affected complications.