Factors predicting success of emergency extracorporeal shockwave lithotripsy (eESWL) in ureteric calculi--a single centre experience from the United Kingdom (UK).

Abstract

Few studies show that "emergency extracorporeal shockwave lithotripsy (eESWL)" reduces the incidence of ureteroscopy in patients with ureteric calculi. We assess success of eESWL and look to study and identify factors which predict successful outcome. We retrospectively studied patients presenting with their first episode of ureteric colic undergoing eESWL (within 72h of presentation) over a 5-year period. Patient's age, gender, stone size and location, time between presentation and ESWL, number of shock waves and ESWL sessions, and Hounsfield units (HU) were recorded. 97 patients (mean age 40years; 76 males, 21 females) were included. 71 patients were stone free after eESWL (73.2%) (group 1) and 26 patients failed treatment and proceeded to ureteroscopy (group 2). The two groups were well matched for age and gender. Mean stone size in group 1 and 2 was 6.4mm and 7.7mm, respectively, (p=0.00141). Stone location was 34, 21, and 16 in upper, middle and lower ureter in group 1 compared to 11, 5, and 10 in group 2, respectively. Mean HU in group 1 was 480 and 612 in group 2 (p value 0.0036). In group 2, significantly, more patients received treatment after 24h compared with group 1 (38 vs 22.5%). The number of shock waves, maximal intensity, and ESWL sessions were not significantly different in the two groups. No complications were noted. eESWL is safe and effective in patients with ureteric colic. Stone size and Hounsfield units are important factors in predicting success. Early treatment (≤24h) minimizes stone impaction and increases the success rate of ESWL.