Aim: to determine main risk factors for complications of ureterolithotripsy.
Materials and methods: a retrospective analysis of the results of 545 ureteroscopies performed in 506 patients with ureteral stones over the past 7 years at the urological clinic named after M.F. Vladimirsky was carried out. The relationship between preoperative and intraoperative factors and complications of ureterolithotripsy was analyzed.
Results. The overall complication rate was 22.4%. The risk of intraoperative complications was proved to increase (p<0.05) along with the stone size, location in proximal ureter, stone impaction for more than 3 weeks and the degree of hydronephrosis. No preoperative stenting or nephrostomy tube prior to ureteroscopy was associated to an increased risk of intraoperative complications (RR=2.88; p=0.03). Patients with preoperative drainage of upper urinary tract has lower probability of intraoperative complications (OR=0.35; p=0.03).
The risk of developing stricture and ureteral obliteration in uncomplicated ureteroscopy was minimal (RR=0.008, p=0.0001). Small ureteral perforation and pronounced mucosal inflammation around the stone have the similar influence on the risk of complications, which was more than 7.5 times (p=0.0001) higher than in uncomplicated ureteroscopy. Large ureteral perforation was associated with the highest risk of stricture formation and ureteral obliteration, which was 64 times (p=0.0001) higher than in uncomplicated ureteroscopy.
Conclusion. The rate of complications of ureterolithotripsy directly depends on the following factors: size and location of the stone, the stone impaction, pre- and intraoperative (nephrostomy tube) drainage of the upper urinary tract, the degree of hydronephrosis, level of bacteriuria and intraoperative trauma complications.

Keywords: ureterolithotripsy, ureteral stones, risk factors