Evaluation of a new multi-basket load-release ureteral stent

A multi-basket ureteral stent was tested and modified to assess feasibility of load-release features intended to release stone(s) if resistance is encountered during stent removal.

Three versions of the stent were evaluated: (1) unaltered stent, (2) one strand of each basket partially cut to 50%, or 75% (3) tube between baskets longitudinally slit. One of the baskets was filled with multiple 3-4-mm stones or a single large 6-mm stone to 20Fr diameter. The force required to release the device through a tube with an 8Fr narrowing was determined. In a separate assessment, urologists used a string attached to the force gauge to exert the maximum force they would be comfortable using in ureteral stent removal.

The unaltered stent was associated with higher release forces or inability to remove the stent: 18.67 +/- 8.35 N when a single large stone was present, compared to 8.46 +/- 2.75 N for multiple small stones. Modified devices with 50% and 75% cut basket strands released at 15.19 +/- 1.54 N, and 10.65 +/- 2.09 N, respectively. The longitudinal slit device released at 3.11 +/- 1.57 N. The maximum force exerted by urologists in simulated stent removal was 7.3 +/- 0.4 N.

Modifications to the multi-basket ureteral stent allow for stent removal in an in vitro model with a narrowing present with stone(s) in the stent baskets. The longitudinal slit modification appears to allow for stent removal with forces low enough to prevent significant ureteral injury, even if ureteral strictures are present.