This randomized controlled trial aims to compare the efficacy and safety of two suction techniques during retrograde flexible ureteroscopy (FURS) for lower calyceal renal stones measuring 1.5-2 cm. The study evaluates Flexible \& Navigable Suction Ureteral Access Sheath (FANS) versus Antegrade Suction (via percutaneous access) in improving stone-free rates (SFR), reducing operative time, and minimizing complications such as bleeding, ureteral injury, and infection. A total of 120 adult patients will be randomized into two groups, undergoing either flexible ureteroscopy (FURS) with Flexible \& Navigable Suction Ureteral Access Sheath (FANS) or flexible ureteroscopy (FURS) with antegrade suction, at Banha University Faculty of Medicine.
Adult patients (≥18 years old)
Patients diagnosed with renal stones (1.5-2 cm) confirmed by non-contrast computed tomography (NCCT)
Patients undergoing flexible ureteroscopy (FURS) as the primary treatment approach
Patients with no active urinary tract infection (UTI) at baseline
Patients with anatomical anomalies (e.g., horseshoe kidney, PUJ obstruction)
Patients with a single functioning kidney
Pregnant women
Patients with a history of urological malignancy