Factors influencing the success of flexible Ureterorenoscopic guided l aser l ithotripsy )

1. No. 055 Factors influencing the success of flexible Ureterorenoscopicguided laser lithotripsy) Barazanchi A1, Davies A1, Smit L2, Holmes M1. 1 Urology Services Ltd. 2 Urology Waikato Ltd. Posters Proudly Supported by: • Introduction • Several modalities exist in the treatment of ureteric and renal calculi. With recent improvement of laser and fibre optic scope technologies, the flexible ureterorenoscope has become mainstream in treatment of upper urinary tract stones. • Several factors influencing the success rate of lithotripsy have been investigated. To date only increasing stone burden and size has been associated with reduction in success rate of lithotripsy1,2. Results 166 patients were included in this study. 10 patients were lost to follow up. Stone Diameter and Stone Burden Diameter of the largest stone and stone burden, calculated as cumulative stone diameters3, were independent risk factors for the success rate of laser lithotripsy. Mean largest stone diameter and stone burden for successful lithotripsy were 9mm and 12mm respectively (N=120), versus 15mm and 24mm respectively (N=46) for unsuccessful lithotripsy (P < 0.0001). Success rate of laser lithotripsy decreased with increasing stone burden. Stone Location Lower pole renal stones had the lowest rate of successful lithotripsy (p <0.05). Ureteric stones had the highest rate of success, but with smaller stone diameters. Consultant and Registrar Cases Compared Registrars had a shorter operative time with a lower success rate (P <0.05) . Factors Not Influencing Success of Lithotripsy Success rate of lithotripsy was not affected by stone Hounsfield Units, time of day for operation, patient gender, ASA score or patient ethnicity. Aim To evaluate the success rate of flexible ureterorenoscopic guided laser lithotripsy of upper tract urinary calculi based on stone, patient and operator specific factors. • Methods • All records for lithotripsy procedures from public and private Hamilton patients for the period August 2008 to August 2012 were reviewed. • All laser lithotripsy procedures using only flexible ureterorenoscope guidance were included for this analysis other procedures excluded. • Stone related clinical events within the first 3 months post lithotripsy were identified. • All radiology was independently reviewed and compared with the report provided by the radiologist. • Data was extracted from patient records with respect to largest stone size, overall stone burden, stone location, Hounsfield Units , surgeon and operative time. • Lithotripsy was only deemed successful if all of the following criteria were met: • Opacities <3mm on imaging. • No further treatments on the same stone within 3 months. • Complete fragmentation of stone(s) based on operation notes. • Statistical analyses performed using GraphPad software, with Chi-Squared test for categorical and Unpaired t-test for continuous data. Acknowledgements I acknowledge Bary P1, Leyland J1, Devcich G1, and Wright W2 for their contribution to my research and presentation. 1 Urology Services Ltd. 2 Urology Waikato Ltd. References 1. Hussain M, Acher P, Penev B, Cynk M. Redefining the limits of flexible ureterorenoscopy. Journal of endourology / Endourological Society. 2011 Jan;25(1):45-9. PubMed PMID: 21050026. 2. Rippel CA, Nikkel L, Lin YK, Danawala Z, Olorunnisomo V, Youssef RF, et al. Residual fragments following ureteroscopic lithotripsy: incidence and predictors on postoperative computerized tomography. The Journal of urology. 2012 Dec;188(6):2246-51. PubMed PMID: 23083650. 3. Ito H, Kawahara T, Terao H, Ogawa T, Yao M, Kubota Y, et al. The most reliable preoperative assessment of renal stone burden as a predictor of stone-free status after flexible ureteroscopy with holmium laser lithotripsy: a single-center experience. Urology. 2012 Sep;80(3):524-8. PubMed PMID: 22658621. . • Conclusions • There is a significant reduction in the success rate of laser lithotripsy, using a flexible ureterorenoscope for larger stone sizes, increased overall stone burden and lower pole stones. • Consultant surgeons tend to have a longer operative time at our centre, yet have a higher success rate for laser lithotripsy of stones. • The results of this study can provide valuable information to help with operative planning, patient information and teaching of registrars.