Purpose: Comparison of effectiveness and safety of ultramini percutaneous nephrolithotomy (UMPNL) and retrograde intrarenal surgery (RIRS) in treatment of moderate-sized renal stones.

Material and methods: The patients scheduled for surgery attributable to renal stones with the greatest diameter of 10 to 25 mm were prospectively analyzed. Patients were randomized into groups with tossing a coin method. The patients who had UMPNL and RIRS were defined as Group I and Group II, respectively. The groups were compared for demograhic data, stone characteristics, operative and postoperative data, stone-free status, and the complications. Student’s t-test and Pearson’s Chi square tests were used for statistical analysis. p < 0.05 was considered as statistically significant.

Results: There were 30 patients in Group I, and 43 patients in Group II. The groups were similar for age, gender, side of the stone, and surface area characteristics of the stone (p = 0.194, p = 0.470, p = 0.990, and p = 0.487, respectively). Stone-free rate was 80% (n = 24) in UMPNL, and 74.4% (n = 32) in RIRS (p = 0.579). Modified Clavien Classification Grade 1 to 2 and 3A to 3B complications were similar in two groups (p = 0.959 and p = 0.192, respectively). Comparison of stone-free rates was 93.3% in UMPNL, and 42.9% in RIRS groups for lower pole stones (p = 0.009). Groups I and II were significantly different for visual analog scale scores for postoperative pain (4.73 ± 1.25 vs 2.30 ± 1.12), hospital stay (2.46 ± 3.02 vs 1.37 ± 1.48 days), and time to return to normal daily life (11.26 ± 5.55 vs 6.65 ± 4.30 days) (p < 0.001, p < 0.001, and p < 0.001, respectively).

Conclusion: Both UMPNL and RIRS procedures are effective and safe methods in treatment of middle-sized renal stones. However, UMPNL is more effective than RIRS in treatment of lower pole stones. RIRS is more advantageous when loss from work is taken into consideration.