Mini-percutaneous nephrolithotomy vs flexible ureteroscopy for 1-2 cm lower pole renal stones: a randomised controlled trial

Objective: To compare the safety and efficacy of flexible ureteroscopy (f-URS) and ambulatory tubeless mini-percutaneous nephrolithotomy (mini-PCNL) in the treatment of 1-2 cm lower calyceal renal stones.

Patients and methods: Patients who underwent f-URS and mini-PCNL for the treatment of 1-2 cm lower calyceal renal stones between October 2020 and November 2023 were evaluated in a randomised controlled trial. A total of 72 patients were included in the study. All patients underwent a computed tomography renal colic scan preoperatively, on postoperative Day 1 (POD 1), and at 3 months follow-up. We compared perioperative outcomes, including operative time and hospital stay. Additionally, we evaluated follow-up outcomes, such as the stone-free rate (SFR) and complications. All patients were discharged home on the same operative day.

Results: There were no significant differences in preoperative baseline data between the two surgical groups. A significantly longer median operative time was reported in the mini-PCNL group (P = 0.04). The median hospital stay was 5 h and 4 h in the mini-PCNL and f-URS groups, respectively (P = 0.14). On POD 1, the SFR, defined as the absence of residual fragments measuring 0 cm, was 50% for mini-PCNL vs 11.1% for f-URS (P < 0.001). When a total cut-off of <0.4 cm was utilised, the SFR was 75% in the mini-PCNL group vs 22.2% in the f-URS cohort (P < 0.001). At 3 months follow-up, the SFR remained favourable for mini-PCNL at 72.2% vs 37.1% for f-URS (P = 0.003), with a cut-off of 0 cm, and it increased to 86.1% for mini-PCNL vs 65.7% for f-URS (P = 0.04) when a total cut-off of <0.4 cm was applied. There was no significant difference in postoperative complications between the two groups. Two patients (5.7%) in the f-URS group required re-treatment.

Conclusions: Ambulatory tubeless mini-PCNL and f-URS are effective treatment options for 1-2 cm lower calyceal renal stones. Both techniques have a comparable hospital stay and complication rates, with a significantly better SFR with mini-PCNL.