Tip-Bendable Suction Ureteral Access Sheath Combined with Gravity-Assisted Supine Positioning (± 20° Trendelenburg/Reverse Trendelenburg) in Retrograde Intrarenal Surgery for Renal Stones ≥3 cm: A Multicenter Retrospective Evaluation of a New Technique

Purpose: To evaluate the safety and efficacy of a novel combined retrograde intrarenal surgery (RIRS) technique utilizing a tip-bendable suction ureteral access sheath (S-UAS) and ±20° gravity-assisted (Trendelenburg/reverse Trendelenburg) supine positioning for treating renal stones ≥3 cm. Methods: A retrospective multicenter study (3 centers) was conducted in 73 patients between October 2023 and January 2025 with renal stones ≥3 cm. A two-phase surgical approach was employed: initial lithotripsy in 20° Trendelenburg position, followed by fragment evacuation in 20° reverse Trendelenburg using S-UAS suction. All procedures utilized flexible ureteroscopy and a 12/14F S-UAS. Perioperative variables—including operative time, hemoglobin drop, need for second-stage procedures, 3-month stone-free rate (SFR), and complications (fever, subcapsular hematoma, and septic shock) graded by the Clavien–Dindo system—were recorded. Results: A total of 73 patients (mean stone size ∼34 mm) were included. Mean operative time was 125 ± 39 minutes. A second-stage RIRS was required in 32.9% of cases. The overall SFR at 3 months was Grade A (60.3%), Grade B (90.4%), and Grade C (97.3%) after one or two sessions. Postoperative fever occurred in 12.3% and subcapsular hematoma in 1.4% of patients; one patient (1.4%) developed urosepsis (septic shock, Clavien IVa) requiring intensive care unit care. No patients had long-term sequelae or required open surgery. On subgroup analysis, patients with high stone density (≥700 Hounsfield units) had higher second-stage RIRS rate. Conclusion: RIRS with a tip-bendable suction sheath combined with gravity-assisted supine positioning (±20° Trendelenburg/Reverse Trendelenburg) for renal stones appears to be a feasible option for managing stones >3 cm and may be particularly suitable for lower-density calculi. Further studies are needed to validate its effectiveness and safety in broader populations.