Endourology & Stone Disease(구연) (E-163) Outcomes of Extracorporeal Shock Wave Lithotripsy in ureteral stone according to ESWL intensity Urology, Ulsan University Hospital, University of Ulsan College of Medicine, Urology, Ulsan University Hospital, University of Ulsan College of Medicine, Urology, Ulsan University Hospital, University of Ulsan College of Medicine, Urology, Ulsan University Hospital, University of Ulsan College of Medicine, Urology, Ulsan University Hospital, University of Ulsan College of Medicine, Urology, Ulsan University Hospital, University of Ulsan College of Medicine, Urology, Ulsan University Hospital, University of Ulsan College of Medicine, Urology, Ulsan University Hospital, University of Ulsan College of Medicine, Urology, Ulsan University Hospital, University of Ulsan College of Medicine Ji Hyung Yoon, Chongsok Chae, Myeong Chan Park, Sejun Park, Seong Cheol Kim, Sungchan Park, Kyung Hyun Moon, Sang Hyeon Cheon, Taekmin Kwon Background: Extracorporeal Shock Wave Lithotripsy (ESWL) has long been used safely as a primary treatment for ureterolithiasis. Also, various methods to improve the success rate of ESWL have been studied. In terms of energy, a "ramping" protocol that gradually increases energy is widely used. However, there are no studies based on ESWL intensity. / Objectives: Therefore, the present study was performed to evaluate the treatment outcomes of ureteral stone according to ESWL intensity. / Materials and Methods: From September 2018 to February 2020, we retrospectively analyzed 150 patients who performed ESWL with Compact Delta/Sigma model that can confirm intensity (a – c and 1 –  6) for treatment of ureteral stones. All of the patients' stones were confirmed by CT examination with/without enhancement, and the size, location, skin to stone distance (SSD), and Hounsfield unit (HU) of the stones were accessed. In addition, patient characteristics including body mass index (BMI) and GFR, which can affect treatment outcomes, were also accessed. The success or failure of ESWL was confirmed according to the session, the factors affecting treatment outcomes were analyzed using a logistic regression model. We also examined the characteristics of stones that had undergone endoscopic removal under general anesthesia due to ESWL failure. / Results and Conclusion: The mean age of the patients was 52.1 years, and mean stone size was 7.2 cm. Of the 150 patients, 82 (54.7%) had stones in proximal ureter, 5 (3.3%) in mid, and 63 (42.0%) in distal. Patients underwent ESWL on average 1.5 times, and the success rate according to the session was 65.3% for the first, 83.3% for the second, and 90.0% for the third, respectively. Complications occurred in 3 patients, but all were mild symptoms of grade 1. In multivariable analysis showed stone size (OR 0.81, CI 0.66-0.99, p=0.049) and HU (OR 0.99, CI 0.98-0.99, p=0.001) were the significant factors affecting success rate after first ESWL session, and the ESWL intensity was not related to success rate. In the case of the 3rd session, stone size (OR 0.78, CI 0.62-0.96, p=0.022) was the only significant factor affecting the success rate. There were 15 patients who underwent endoscopic removal due to ESWL failure, and they had stones with larger (10.5mm vs. 6.8mm, p=0.001) and higher HU (919.7 vs. 651.9, p=0.001).  In conclusions, stone size and HU have a great influence on the ESWL success rate, and several times ESWL or endoscopic remove are often required when the stone size is large and HU is high. ESWL intensity is not significantly related to the success rate, so it is recommended to adjust it according to patient pain or degree of stone fragmentation.   keywords : Ureteral calculi, Lithotripsy, Extracorporeal Shockwave Therapy