Comparison of nitinol tipless stone baskets in an in vitro caliceal model

Purpose: Tipless stone baskets facilitate caliceal calculi extraction during flexible ureteroscopy. We evaluated the stone capture rate of 9 commercially available tipless stone baskets in an in vitro model using novice and expert operators. Materials and Methods: The Microvasive Zerotip (2.4Fr, 3.0Fr), Cook N-Circle (2.2Fr, 3.0Fr, 3.2Fr), Bard Dimension (3.0Fr, Sacred Heart Medical Halo (1.9Fr), Vantage (1.9Fr) and Circon-ACMI Sur-Catch-NT (3.0Fr) were tested by 3 novice and 3 experienced basket operators. Each operator performed stone extraction of 2, 5 and 8 mm calculi (size determined by digital caliper with 3 repetitions of each basket. The time to extraction of the calculus from a convex based test tube caliceal model was recorded. Statistical analysis was performed using repeated measures ANOVA and Fisher's pairwise comparisons. Results: After a learning curve of 27 basket retrievals, there was no significant difference in stone capture times between novice (38 ± 54 seconds) and expert operators (32 ± 49 seconds, p = 0.174). For total stone capture (all sizes) the Sacred Heart Halo resulted in the most rapid stone extraction (17 ± 14 seconds) by novices and experts, while the Sur-Catch NT resulted in the slowest stone extraction (78 ± 90, seconds, p = 0.001). The Halo (14 ± 9 seconds) and Vantage (19 ± 12 seconds) baskets were significantly faster for 2 mm calculi than the N-Circle (73 ± 60 seconds, p = 0.006), Sur-Catch (169 ± 85 seconds, p = 0.0005) and Dimension (73 ± 70 seconds, p = 0.017). The Zerotip functioned well for 2 mm calculi in the hands of expert operators (15 ± 9 seconds) but not novice operators (94 ± 95 seconds). The Sur-Catch NT was significantly slower for 2 mm calculi than the N-Circle (p = 0.01), Dimension (p = .03), Halo (p = .0005), Vantage (p = .001) and Zerotip (p = .002). For 5 mm calculi the Halo was superior (12 ± 8 seconds), while the Zerotip were superior for 8 mm calculi (8 ± 3 seconds) compared to the N-Circle (23 ± 28 seconds, p = 0.026), Halo (26 ± 18 seconds, p = 0.021) and Vantage (23 ± 15 seconds, p = 0.006). Conclusions: The Sacred Heart Halo and Vantage baskets resulted in the most expeditious stone extraction, especially for 2 to 5 mm calculi while the Microvasive Zerotip was optimal for 8 mm calculi. The Sur-Catch NT had the slowest stone capture rate for all stone sizes. Caliceal models of stone basketing may be useful to train novice urology residents and nursing assistants.