Abstract
BACKGROUND: Management of upper urinary tract stones with moderate-to-severe hydronephrosis remains challenging due to altered renal anatomy and higher complication risks. Flexible negative-pressure ureteral sheath lithotripsy (FANS) has emerged as a minimally invasive alternative to miniaturized percutaneous nephrolithotomy (mini-PCNL). This study compared the efficacy and safety of FANS and mini-PCNL in this patient population. METHODS: A total of 125 patients with upper urinary tract stones and moderate-to-severe hydronephrosis who underwent either FANS (n = 57) or mini-PCNL (n = 68) between June 2024 and June 2025 were retrospectively analyzed. Baseline demographics, stone characteristics, operative parameters, perioperative laboratory changes, hospital stay, immediate stone-free rate (SFR) and finial SFR, and postoperative complications were assessed. RESULTS: Baseline characteristics (age, BMI, stone burden, comorbidities, and hydronephrosis degree) were comparable between groups. The FANS group had a longer operative time (70 vs. 60 min, P = 0.006) but a shorter stay of hospital (2 vs. 3 days, P = 0.008) and smaller hemoglobin drop (8.0 vs. 11.0 g/L, P = 0.031). WBC changes, eGFR drop, immediate SFR (80.7% vs. 80.9%) and finial SFR (89.5% (51/57) vs. 88.2% (60/68)) were similar. The overall complication rate was lower with FANS (5.9% (4/57) vs. 25.0% (17/68), P = 0.011), and no severe complications occurred, whereas mini-PCNL included several Grade 3b events. CONCLUSIONS: Both FANS and mini-PCNL achieved comparable stone clearance in moderate-to-severe hydronephrosis. However, FANS offered reduced bleeding, faster recovery, and fewer complications, indicating its potential role as a safer and less invasive option for patients with complex upper urinary tract anatomy.