Comparative evaluation of Stone Cone and NTrap for prevention of stone retropulsion during ureteroscopic lithotripsy for upper and mid-ureteric calculi

Abstract Background Stone retropulsion during ureteroscopic lithotripsy (URSL) adversely affects stone-free rates and may increase the need for auxiliary procedures, particularly in upper and mid-ureteric calculi. Mechanical anti-retropulsion devices such as Stone Cone and NTrap are commonly used to prevent proximal migration of stone fragments. Objective Primary objective: Stone-free rate at one month, defined as absence of residual calculi > 2 mm on non-contrast CT-KUB. Secondary Objective: Operative time,Intraoperative and postoperative complications (Clavien–Dindo classification),Requirement of auxiliary procedures and Duration of hospital stay. Materials and methods In this prospective randomized study, 56 patients with upper or mid-ureteric calculi were randomized into two groups (n = 28 each) using sealed envelope method. Group A underwent URSL using NTrap, while Group B underwent URSL using Stone Cone. The primary outcome was stone-free rate (SFR), defined as absence of residual calculi >2 mm on non-contrast computed tomography at one month. Secondary outcomes included operative time, intraoperative and postoperative complications, need for auxiliary procedures, and duration of hospital stay. The radiologist assessing the primary outcome was blinded to group allocation. Results The mean stone size was 11.08 ± 2.5 mm, and mean stone density was 1028 ± 331 HU. Operative time was comparable between groups (55.7 ± 21.1 vs. 56.2 ± 20.6 minutes). The SFR was 85.7% in the NTrap group and 96.4% in the Stone Cone group (p = 0.160) Although the observed rate was numerically higher with Stone Cone, no statistically significant between-group difference was detected. Complications were minimal and predominantly minor in both groups. Auxiliary procedures were required in four patients in the NTrap group and one patient in the Stone Cone group. Conclusion Both Stone Cone and NTrap are safe and effective anti-retropulsion devices during URSL. Although Stone Cone demonstrated a higher stone-free rate, the difference was not statistically significant. These findings support the use of either device based on surgeon preference, local availability, cost, and provide a basis for future adequately powered multicentre trials.