First prize: A novel device to prevent stone fragment migration during percutaneous lithotripsy

Purpose: We developed a novel device to capture stones in vivo in an enclosed bag (PercSac) to prevent dispersion of stone fragments during percutaneous nephrolithotomy (PCNL) or cystolitholapaxy. We report on our initial feasibility trials of the PercSac device.

Materials and Methods: PercSac consists of a specially designed polyethylene bag that is fitted over the shaft of a rigid nephroscope. The bag is used to first entrap the target stone, then tighten around it to allow fragmentation within the bag. Matched pairs of 10 canine bladder stones (2.5cm maximum diameter) were fragmented in a human bladder model using the CyberWand™ (Olympus America, Inc.), and the procedure was assessed for markers of efficiency and effectiveness.

Results: Median time to entrap the stone within the PercSac was 67 seconds (range 51-185sec). Median time for stone fragmentation was significantly shorter with the PercSac than without (182.0sec [range 108-221] vs 296.5sec [range 226-398], P=0.004). Overall, however, there was no significant difference in the total time to entrap and fragment the stones between the two groups. A stone-free state was not achieved for any trial without the PercSac, while 9 of 10 trials with the PercSac resulted in a stone-free state.

Conclusions: Use of the PercSac in conjunction with stone fragmentation has the potential to reduce the occurrence of residual fragments after PCNL or cystolitholapaxy. Further in vitro testing in a kidney model is planned.