F-URS with FANS versus mPCNL for 2-3 cm UUTS: a RCT with a subgroup analysis of 2-2.5 cm stones

To evaluate the safety and efficacy of flexible ureteroscopy (f-URS) with a flexible and navigable suction ureteral access sheath (FANS) compared with mini-percutaneous nephrolithotomy (mPCNL) in the treatment of 2-3 cm upper urinary tract stones (UUTS), with a prespecified subgroup analysis for stones ≥2 to <2.5 cm.

This randomized controlled trial enrolled 326 patients with 2-3 cm UUTS between June 2023 and December 2025. Patients were randomly assigned in a 1:1 ratio to undergo either f-URS with FANS or mPCNL. A prespecified subgroup analysis was conducted for stones measuring ≥2 to <2.5 cm. The primary outcomes were the immediate and 1-month stone-free rate (SFR). Secondary outcomes included the operative duration, decrease in haemoglobin, hospital stay, and complication rate.

The baseline characteristics were comparable between the two groups. In the overall 2-3 cm cohort, the FANS group achieved immediate and 1-month SFRs comparable to those of the mPCNL group. Although the operative time was longer in the FANS group, it was associated with significantly less haemoglobin loss and a shorter hospital stay, with no significant difference in infection-related complications. Notably, in the subgroup of stones ≥2 to <2.5 cm, the FANS group demonstrated a non-inferior SFR at both time points, and the operative time was not significantly longer than that of the mPCNL group.

For 2-3 cm UUTS, f-URS with FANS offers a SFR comparable to that of mPCNL, along with the advantages of reduced blood loss and shorter hospitalization. In the ≥2 to <2.5 cm subgroup, FANS shows comprehensive benefits over mPCNL. These findings support FANS as an effective alternative to mPCNL for 2-3 cm stones and a potentially preferred option for stones measuring 2-2.5 cm.