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Dextranomer/Hyaluronic Acid Endoscopic Injection Simulator

Saturday, October 20, 2012
Grand Ballroom A/B (Hilton Riverside)
Guy Hidas, Department of Urology, University of California Irvine, Children Hospital Orange County, Orange, CA, Elspeth M. McDougall, Department of Urology, University of California Irvine, Minimally Invasive Surgery Education Center, CA and Antoine E. Khoury, MD, FAAP, Urology, University of California Irvine, Children's Hospital of Orange, Orange California, USA, Orange, CA


Published success rates of dextranomer/hyaluronic acid(Dx/HA) injection for pediatric vesicoureteral reflux(VUR) correction vary widely.  Increased surgeon experience has been shown to have an important role in these results, and it is well known that endoscopic injection has a definite learning curve, especially for higher VUR grades. Dx/HA needle injection is a 1 to 2-minute, highly confined, unforgiving implantation of a discrete 1 to 3 subucosaly with little room for, adjustment, intraoperative correction or revision. Multiple needle punctures have been shown to decrease the success rate. Nevertheless, to our knowledge no validated simulator has been developed to provide the opportunity to learn and practice those skills that can be transferred to the operating room.  We present a porcine bladder simulator model for training and assessment of the surgical skills for the Dx/Ha endoscopic injection technique.


We developed a porcine bladder model placed in a training box. We positioned the porcine bladders with the distal ureters and urethra in 20x20cm polystyrene box and performed cystoscopy as well as Submucosal injection, Subtrigonal injection and Double Hit injection of Dx/HA. Dx/HA syringes and needles were used. In order to simulate Dx/HA consistency we utilized Surgical K-Y lubricant gel as the injecting compound. Following injection the bladders were opened to appreciate the quality of the injection mound and provide the trainee with immediate feedback. Content validity testing of the simulator was performed by four pediatric urologists with over 15 years of experience and 20 mean injection procedure annually. Experts were asked to perform bilateral double HIT injection. After the procedure the experts completed a questionnaire designed to evaluate the realism of each step of the injection procedure on the simulator compared to an actual procedure.  


Overall the model demonstrated good content validity by all experts (mean questionnaire score 92%). Mean post injection questionnaire scores measured the ability of the simulator to simulate realistically each steps of the actual procedure were 94% for the cystoscopy, 94% for the Ureteral orifice identification, 87% for the ureteral orifice hydrodistention part of the procedure, 94% for the first and second injection, 100% for the shape of the mound after the injection. 75% for the Viscosity of the material used for simulate injection. 


Dx/HA Endoscopic Injection Simulator realistically simulate the actual clinical procedure. This simulator may be an effective teaching tool to improve the early learning curve and provide a greater understanding of the components of successful endoscopic VUR correction.