Influence of pre-stenting on flexible and navigable suction (FANS) access sheath outcomes. Results of a prospective multicentre study by the EAU Section of Endourology and the global FANS collaborative group.

Introduction: Pre-stenting remains a subject of debate, and its influence on FANS assisted ureteroscopy is unclear. The global FANS collaborative group aims to address the influence of pre-stenting on FANS-assisted ureterorenoscopy (URS).

Material and methods: This prospective multicentre study assesses the outcomes of 394 patients undergoing FANS-assisted ureteroscopy for renal stones. Patients were stratified into a non-pre-stented (group 1, n = 163) and pre-stented group (group 2, n = 231). Data on demographics, stone characteristics, operative parameters, and postoperative 30-day outcomes were analysed. Statistical analyses, including multivariate regression, were performed for stone-free rates (SFR) and complications. SFR was defined by bone window on non-contrast computed tomography (CT).

Results: Pre-stented patients had a higher prevalence of positive urine culture treated with preoperative antibiotics (23.8% vs 12.3%, p = 0.006). Larger stone volumes were noted (1,306 mm³ vs 1,200 mm³, p = 0.027) in group 1. Postoperative complications were minor. Sepsis was not reported in either group. Group 1 had a higher incidence of low-grade Traxer grade 1 ureteric injuries (4.3% vs 0.4%, p = 0.021). FANS resulted in high overall SFRs of 97.5% and 97.0% in groups 1 and group 2. Multivariate analysis showed no statistical difference in SFR between the groups (63.2% vs 53.2%, p = 0.063). Only thulium fibre laser (TFL) and stone volume were significant predictors of residual fragments (RF).

Conclusions: Pre-stenting for FANS is not mandatory irrespective of stone location and volume. The use of TFL and stone volume significantly influenced SFR, while FANS itself proved highly effective in achieving high SFR.