Logistic regression reveals the stone-clearance ratio of ESWL after the first trial is 0.27 times less than of URS (KTC 95% = [0.14 - 0.51]), non-statistic significant after second trial (RR = 1.26 [0.62 - 2.57]; p>0.5) but on the third trial, 2.22 times more than of URS (KTC = 95% = [1.02 - 4.84]).