Extracorporeal shock wave lithotripsy of lower ureteric stones: Outcome and criteria for success

OBJECTIVE To evaluate the efficacy of extracorporeal shock wave lithotripsy (ESWL) for distal ureteric calculi (DUC) and to determine variables that could affect the outcome results. PATIENTS AND METHODS Between April 2004 and February 2008, 100 patients with a solitary DUC were treated with in situ ESWL using a lithotripter (Lithostar Plus, Siemens, Erlangen, Germany). The outcome of treatment was evaluated after 3 months. The patients' clinical and radiological findings, as well as stone characteristics, were reviewed and correlated with the stone-free rate (SFR). RESULTS After in situ ESWL, 84 patients (84%) were stone-free (after one session in 57 and after two in 27). From a univariate analysis only three factors had a significant impact on the SFR, i.e. the body mass index (BMI), stone length and stone width. The SFR was significantly lower in obese patients than in normal and overweight patients (P = 0.019). Stone width ⩾8 mm was associated with a SFR of 64% (14/22), compared with 89.7% (70/78) for those with a stone width of <8 mm (P = 0.007). The SFR was 86.8% (66/76) for a stone length of ⩽10 mm and 71% (17/24) for a stone length of >10 mm (P = 0.016). On multivariate analysis, BMI, stone width and stone length maintained their statistical significance. CONCLUSION Primary in situ ESWL remains an effective and safe form of treatment for DUC. The length and transverse diameter of the stone, together with the BMI of the patient, were the only significant predictors of the overall success of ESWL.