Safety and Effectiveness of Antegrade Flexible Ureteroscopy-Assisted Percutaneous Nephrolithotomy for Staghorn Calculi

Objective This study aims to evaluate the safety and efficacy of antegrade flexible ureteroscopy-assisted PCNL for the treatment of staghorn calculi, compared with standard PCNL. Methods This prospective, multicenter, randomized controlled trial plans to enroll 420 patients with staghorn calculi, randomly assigned into two groups: the experimental group (antegrade flexible ureteroscopy-assisted PCNL, n=210) and the control group (standard PCNL, n=210). The primary endpoint is stone-free rate (defined as no residual fragment ≥2 mm on postoperative CT). Secondary endpoints include operative time, number of percutaneous tracts, rate of secondary procedures, hemoglobin decrease, postoperative complications (Clavien-Dindo classification), and length of hospital stay. All patients will undergo CT evaluation on postoperative day 2. Subgroup analysis will be performed according to the number of stone branches (≥5 vs \<5).