Real-world DISS practice combined with and without access sheath: insights from the global DISS dataset: a EAU endourology study

Purpose: The role of ureteral access sheath (UAS) during flexible ureteroscopy (fURS) remains undecided in the era of direct in-scope suction (DISS), which subserves dust and debris removal with active intrarenal pressure control. This study aims to evaluate the utility of UAS on perioperative outcomes in patients undergoing DISS-assisted fURS. Methods: This prospective, multicentre study analysed data from an international registry of patients who underwent successful fURS with DISS at 16 centres across 14 countries between May and December 2025. Patients were grouped based on whether UAS was used. All participants had one non-contrast CT scans (NCCT) before and at 30 days post operatively. 100% Stone-free rate (SFR) was defined as zero residual fragment (ZFR) on NCCT in bone window (Grade A) or overall stone free (OSF) was Grade A + B where grade B reported a single RF of 2 mm. The study recorded perioperative outcomes, immediate Clavien-Dindo complications and new anatomical anomalies on 3 month imaging. Multivariable logistic regression identified factors that predicted SFR and complications. Results: A total of 540 patients were divided into Group1 undergoing DISS without UAS 296 (54.8%), and Group2 had DISS with UAS 244 (45.2%). ZRF Grade A (Group1vs Group2) was 72.6% vs. 70% and OSF (grade A + B) was 95.9% vs. 88.9% (p = 0.011) respectively but no significant differences in planned re-intervention. Group2 cohort including larger stone burden (12.0 vs. 10.0 mm, p = 0.016), multiplicity higher pre-stenting (57.0% vs. 15.2%, p < 0.001) and more complex cases, operative time was significantly longer in this cohort (64 vs. 39 min, p < 0.001). Although OSF (Grade A + B) rates were high in both groups, they were significantly higher in the non-UAS cohort compared with the UAS cohort (95.9% vs. 88.9%, p = 0.011). Fever > 38.C was significantly higher in Group 2(11.5 vs. 2.7%, p < 0.001) as was 30 day any cause re-admission (7% vs. 15, p < 0.001) with zero sepsis case. Multivariate analysis did not reveal any specific association for ZRF but the use of UAS (OR 6.52, 3.52-12.41, p < 0.001) and pre-stenting (OR 2.63, 1.44-4.90, p,0.002) increases the odds for 30 day complications. Conclusions: DISS with UAS (conventional or Flexible and Navigable Suction access sheath FANS) is preferred in fURS for larger, multiple, or complex stones. Non-UAS DISS is a safe, effective option for smaller, simpler cases, showing high ZRF and OSF rates with fewer low grade complications. Dusting with simultaneous aspiration removes fragments efficiently, may extend operative times, and can reduce post-operative stenting without increasing readmissions or infection risk. These results support tailoring DISS management to individual cases.