Objective. Systematization of complications of endoscopic surgery for nephrolithiasis due to improved Clavien-Dindo classification.

Materials and methods. Retrospectively reviewed the records of 1027 patients with upper urinary tract stones. Endoscopic procedures were performed by the standard technique, percutaneous intervention with the patient on his abdomen in 948 cases. In 79 patients stones were removed transurethrally. Pneumatic lithotripsy was perfromed.

Results. In the postoperative period, 180 (17.5%) patients had 235 complications. To eliminate them 59 additional interventions were perfromed, 26 of them –with general anesthesia. Clinically significant residual stones after interventions for simple stones in 15 patients were evaluated as a complication. On the classification of Clavien-Dindo postoperative complications were evaluated by five degrees: I degree - 64 (6.2%) patients; II degree - 111 (10.8%), grade IIIa - 33 (3,2%), IIIb degree - 39 (3.8%), IVa degree - 2 (0,2%), IVb degree - 1 (0,1%); V degree - 0.

Conclusions.Clavien-Dindo classification of complications can be considered as a versatile and adaptable for an objective assessment of the severity of post-operative complications of nephrolithiasis endoscopic treatment. The complication rate is not a measure for severity of complications. Due to the classification of Clavien-Dindo 70,0% considered mild complications (I or II), and 30,0% - more severe (III and IV), and to eliminate them additional invasive procedures were required.