Redefining the limits of flexible ureterorenoscopy.

BACKGROUND AND PURPOSE: Flexible ureterorenoscopic holmium laser lithotripsy allows retrograde management of renal calculi that previously needed alternative strategies. This study assesses the influences of stone size, density, and location on treatment outcomes from a large series. PATIENTS AND METHODS: Data concerning patients who presented for ureterorenoscopic laser lithotripsy between May 2005 and September 2008 were retrospectively analyzed. Single-treatment success was defined as satisfactory visual clearance of stone bulk, radiopacities less than 2 mm on noncontrast CT, and no further treatment. RESULTS: One hundred and eighty-five patients had 236 treatments (median=51 years; range 18-83 years). Overall success rate was 90.7%. The mean ± standard deviation (SD) stone size was 13.1 ± 8.5 mm with significant differences between the successful (11.6 ± 6.7 mm) and nonsuccessful (27.8 ± 10.0 mm) outcome groups (P<0.0001, unpaired t test). Of treatments for stone size ≤ 20 mm, 96.5% were successful. Of 36 patients with stone size >20 mm, 21 (58.3%) were stone free after one treatment and 31 (86.1%) after two treatments. Hounsfield unit data did not differ significantly between the groups (mean ± SD 858 ± 388 vs 1115 ± 643, P=0.146, unpaired t test). Stone locations were: Renal pelvis, caliceal diverticula, and upper pole, midpolar, and lower pole in 61, 9, 24, 27, and 115 cases with success rates of 85%, 100%, 83%, 93%, and 94%, respectively (P=0.899, chi-square test). CONCLUSION: Clearance rates of >90% can be achieved for stones up to 20 mm with flexible ureterorenoscopy and holmium laser lithotripsy, but with larger stones, the stone-free rates reduce significantly. Therefore, 20 mm should be regarded as the upper limit of stone size that can be cleared in a single procedure. Stone density and location do not influence outcome.