To compare the success and complication rates in the treatment of ureteral stones with a 7.5F versus a 10F ureteroscope.

A total of 100 patients who were scheduled for ureteroscopy to treat ureteral calculi between December 2000 and December 2002 were randomly assigned to procedures with a 7.5F (group 1; n = 50) or 10F (group 2; n = 50) ureteroscope. The group results were compared.

Group 1 had 36 distal, 9 middle, and 5 proximal ureteral stones. Group 2 had 37 distal, 6 middle, and 7 proximal ureteral stones. No statistically significant differences were noted between the two groups with respect to the mean stone size or operation time (P = 0.175 and P = 0.636, respectively). Pneumatic lithotripsy was used in 62% and 50% of the procedures in group 1 and 2, respectively, and stones or fragments were retrieved with basket catheters in 92% and 76% of the group procedures, respectively. The difference between the group rates for successful basket catheter extraction was statistically significant (P = 0.029). Of the patients in group 1 and 2, 84% and 80%, respectively, were stone free after a single procedure (P = 0.603). The corresponding failure rates in the two groups were 6% and 12% (P = 0.295), and the corresponding early and late complication rates in the two groups were 6% and 4% (P = 0.646). None of the patients in group 1 developed late complications. One individual (2%) in group 2 developed ureteral stenosis during long-term follow-up (P = 0.315).

The success and failure rates revealed better outcomes for treatment of ureteral calculi with a 7.5F ureteroscope, but the differences were not statistically significant. The complication rates were similar between the two groups. Basket catheters were used more frequently with the 7.5F scope, and the rates of in situ lithotripsy and postoperative ureteral stent placement were also greater in patients treated with this instrument.