Risk of bleeding after retrograde intrarenal surgery vs miniaturised percutaneous nephrolithotomy for 10-20 mm renal stones: a not so different safety profile

Objective: To assess differences in bleeding risk between retrograde intrarenal surgery (RIRS) and minimally invasive miniaturised percutaneous nephrolithotomy (mini-PCNL) for 10–20 mm renal stones. Patients and methods: A total of 176 patients with a renal stone between 10 and 20 mm were treated. For all patients the Stone Management According to Size-Hardness (SMASH) score was calculated: Hounsfield units × stone maximum size (cm)/100. Patients with score of <15 underwent RIRS (90 patients, Group A), whereas patients with score ≥15 underwent mini-PCNL (86 patients, Group B). In both groups the Cyber Ho laser was used. A statistical analysis was carried out to assess differences in the risk of bleeding. Results: Preoperative features were comparable. The mean maximum stone diameter was 17.1 and 16.8 mm in Groups A and B, respectively (P = 0.13). The stone-free rate was comparable (87.8% vs 95.3%, P = 0.07). The overall complication rate was 14.4% and 18.6% in Groups A and B, respectively (P = 0.09). Gross haematuria was observed in five cases (5.5%) after RIRS and seven (8.1%) after mini-PCNL (P = 0.07). The mean haemoglobin drop was 12 and 2 g/L at the first and third postoperative day after RIRS vs 17 and 3 g/L after mini-PCNL (P = 0.06 and P = 0.21, respectively). Blood transfusions and renal embolisation were never necessary. Conclusion: When managing renal stones between 10 and 20 mm taking into account both size and hardness with the application of the SMASH score, RIRS and mini-PCNL show comparable efficacy. A higher bleeding risk has been expected with percutaneous approaches; however, in our cohort the incidence of clinically significant bleeding was low and comparable between the two groups when adopting mini-PCNL.