PD19-05 THE OPTIMAL GUIDEWIRE TYPE AND EFFECT OF PRIOR USE ON THE EASE OF URETERAL STENT INSERTION

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INTRODUCTION AND OBJECTIVES: Ureteral stent insertion is a frequent procedure in endourology, with no clear consensus on the best wire type to facilitate stent insertion. Use of wires may result in deterioration of their protective coating, requiring greater force for stent insertion. The purpose of this study was to identify the effect of wire type, and prior use, upon average insertion force needed for a 6Fr ureteral stent. METHODS: Stent insertion was tested using an ex vivo porcine urinary tract model with continuous water infusion (1cc/min) to simulate urine production. For each trial, a new, soft, 6Fr Cook JJ ureteral stent was advanced over new and used 0.03800 diameter guide wires including the Glidewire (Terumo), Standard Teflon-coated wire (Cook), Superstiff wire (Cook), Sensor wire (Boston Scientific), Zip-wire (Boston Scientific), and Zebra wire (Boston Scientific). A Mark-10 digital force gauge was attached to the stent, and at a constant advancing rate of 2 rotations per second, the forces to advance the stent over the wire were calculated. 10 trials of stent insertion were randomly performed on 12 new and 12 used guide wires (total of 240 placements). RESULTS: The new Glidewire had the lowest average force required for stent advancement (0.18N). The forces for insertion of all other new wires were significantly higher; Standard (1.25N; p<0.01), Superstiff (2.03N; p<0.01), Sensor (1.87; p<0.01), Zip (0.22N; p<0.01), and Zebra (0.61; p<0.01). When comparing the average insertion force between new and used wires, the used wires required greater mean force in the Standard (2.42N vs. 1.25N; p <0.01), Superstiff (2.68N vs. 2.03N; p <0.01), and Zipwire (0.36N vs. 0.22N; p <.01), but there was no statistical difference between used and new fibers in the Glidewire (0.28N vs. 0.18N; p1⁄40.14), Sensor ( 1.66N vs. 1.87N; p1⁄40.18) and Zebra wire (0.59N vs.0.61N; p1⁄40.67). CONCLUSIONS: The Glidewire resulted in the lowest force for ureteral stent insertion. It may be used several times with no significant effect on ureteral stent insertion force due its resilient lubricious hydrophilic coating. Employing a used Standard, Superstiff and Zip-wire may result in additional stent insertion force. Knowledge of the forces required for stent insertion over various guide wires may allow surgeons to improve the ease and safety of stent placement.