Evaluating factors that affect the outcome of kidneys stone free rate after extracorporeal shock wave lithotripsy

Background: Extracorporeal shock wave lithotripsy (ESWL) remain the predominant therapy for renal calculi. The proper selection of case for therapy by evaluating stone related factors: size, density, and skin-stone distance (SSD) based on non-contrast computed tomography (NCCT), will allow the case to be treated with the most efficient method to achieve a stone free status with low morbidity. Objective: To investigate the effect of stone attenuation, skin-to-stone distance and stone size measured by non-contrast computerized tomography on the outcome of the treatment of renal stone by extracorporeal shock wave lithotripsy. Methods: A prospective experimental study was performed at Department of Urology, Medical City Complex. Starting from July 2013 to December 2015; a total of 70 cases whom age ranged from 20 to 55 years, with renal stone were included in this study and referred for extracorporeal shock wave lithotripsy. Some stone related parameters were assessed by non- contrast computed Tomography. These parameters were linked to the outcome of the treatment. Results: After ESWL, 29 cases (41%) were stone free, 16 cases (22.8%) had complete fragmentation, and 25 cases (35.7%) of 70 cases had incomplete fragmentation. In patients with successful outcomes (stone-free status or complete fragmentation), the average stone attenuation was 839 ± 280 HU, whereas cases with unsuccessful outcomes (incomplete fragmentation) showed a higher mean attenuation of 1060 ± 250 HU (P