Abstract
OBJECTIVE: This study aims to evaluate the safety, efficacy and clinical outcomes of elective flexible ureteroscopy using flexible and navigable suction ureteral access sheaths (FANS) in patients with upper tract infectious stones following initial management of systemic urinary tract infections (UTIs). MATERIALS AND METHODS: We conducted a multicentre prospective analysis of patients with infectious ureteral or kidney stones (struvite or calcium carbonate-apatite) who underwent flexible ureteroscopy using FANS between March 2024 and March 2025. All patients had prior systemic UTI management with a minimum 6-week interval before definitive stone treatment. Stone-free rate was assessed at 30 days using a CT scan. RESULTS: The cohort included 144 patients (median age 51 years, 70.1% female) with a median stone diameter of 1.9 cm. 20.1% had initially received only antibiotic treatment, whereas 79.9% had also received emergency drainage. Forty-seven patients (32.6%) had emphysematous pyelonephritis at initial presentation. Median operative time was 40 min with a 1-day hospital stay. Notable findings included zero cases of sepsis and a 29.9% rate of postoperative fever requiring extended antibiotics up to 2 weeks. Zero residual fragments were achieved in 48.6% and a single fragment up to 2 mm in 43.8% of patients (92.4% combined stone-free rate). Renal function improved at 30 days (median creatinine decrease -15 μmol/L) and 3 months (-18 μmol/L). Fever rate was 29.8% in the emphysematous pyelonephritis subgroup. CONCLUSIONS: Elective flexible ureteroscopy using FANS for upper tract infectious stones is feasible for its excellent safety profile with no sepsis cases and high stone-free rates. FANS technology appears to offer significant advantages in this challenging patient population by mitigating postoperative sepsis due to debris aspiration, reduction of pyelovenous backflow of contaminated irrigation fluids and improved stone fragment evacuation.