Clavien classification of semirigid ureteroscopy complications: a prospective study

To prospectively report and grade the perioperative complications of ureteroscopy (URS) for stone removal using a semirigid ureteroscope with the modified Clavien classification system and to identify the determinants of the complications.

From August 2010 to November 2011, the prospective data from 120 consecutive patients (71 men and 49 women) who had undergone primary unstented URS at a resident training center were analyzed. Patients with renal failure, pyonephrosis, diabetes mellitus, hypertension, and congenital ureteral abnormalities were excluded (n = 29). The data recorded included patient demographics, stone size and location, and complications according to the modified Clavien classification system.

Of the 120 patients, 36 (30%) experienced 79 complications. The stone size was ≤ 10 mm in 56 and >10 mm in 64 patients. The stone location was the lower, mid-, and upper ureter in 62, 58, and 3 patients, respectively. The latter 3 were excluded because of the small sample size. Grade 1, 2, 3a, 3b, 4a, and 4b complications were encountered in 46 (38.3%), 18 (15%), 3 (2.5%), 10 (8.3%), 1 (0.8%), and 1 (0.8%) patient, respectively. The incidence of complications was greater for stones >10 mm, a mid- versus distal ureteral location, impacted stones, and surgery performed by a resident. The incidence was not affected by patient sex, stone laterality, or lithotripter type. The patients with complications had a longer operative time (75 vs 46.5 minutes), longer hospitalization (4.8 vs 1.5 days), and lower stone-free rate (64% vs 97%).

Most complications were grade 1-3 (98%), and grade 4 complications were rare (<2%) with URS. The present study is probably the first to prospectively study the complications of URS using the modified Clavien classification system.