The novel flexible and navigable suction (FANS) ureteral access sheath (UAS) offers benefits such as controlling intrarenal pressure (IRP) and achieving high stone-free status (SFS) with minimal serious adverse events Beyond SFS and IRP-related safety, the rising costs associated with disposable ureteroscopes and high-power laser systems have become a growing concern. Could FANS-UAS potentially reduce the reliance on high-power lasers in RIRS? This study compared the effectiveness, efficiency, and safety of FANS-UAS with low-power holmium laser to conventional UAS with high-power holmium laser in RIRS.

Between August 2022 and February 2024, patients aged ≥ 18 years undergoing RIRS for renal stones were enrolled. Exclusion criteria included uncontrolled urinary tract infections, ureteral stones, and abnormal anatomy. FANS used a low-power holmium laser (2J, 10 Hz), while cUAS employed high-power settings (dusting: 0.4–0.8J, 30–50 Hz; fragmentation: 1.2–2.0J, 15–25 Hz). Primary outcomes were SFS rates on day 1, week 1, and month 1 post-operation and operative time. SFS was categorized as grade A (complete), grade B (≤2 mm fragments), and grade C (≥2 mm fragments) (Figure 2). Multivariable regression analyzed predictors of SFS and operative time. Secondary outcomes included postoperative complications.

The study included 41 males (68.3%) and 29 females (31.7%) with a median age of 55.5 years (IQR: 47–65.5). A single urologist performed 34 cUAS and 36 FANS procedures. Stones were commonly located in the UPJ/renal pelvis and lower calyces. Mean stone size was 13.63 × 8.35 mm (cUAS) and 14.47 × 9.07 mm (FANS). Hard stones (density ≥ 1000 HU) were more frequent in FANS (72.2%) than cUAS (61.8%). FANS achieved higher SFS rates at day 1 (63% vs. 23.5%) and week 1 (66.7% vs. 35.2%; p<0.05), but not at month 1 (72.2% vs. 50%, p=0.11) (Figure2). In multivariate ordinal regression models, using FANS significantly increased the degree of stone-free status in the first day, first week and first month. (reference: cUAS, odd ratio [OR] = 5.07, 4.47 and 3.69; p = 0.003, 0.008 and 0.031, respectively) (Table 1). FANS reduced operative time (60 ± 26.5 min vs. 69.2± 30.1 min, p= 0.028). Regression analysis confirmed FANS use and greater stone area were predictors of operative time (p=0.004, p<0.001). Infectious complications occurred in 5.9% (cUAS) and 8.4% (FANS), with no significant difference (p=0.542). Serious adverse events were negligible in both groups.

RIRS with FANS-UAS achieved higher early SFS rates and shorter operative times compared to cUAS, even with low-power laser. FANS-UAS, offering efficiency and minimal complications, may reduce reliance on high-power lasers, lowering medical costs and energy use.