[Stone burden on extracorporeal shock wave lithotripsy].

Based on the 89 stones treated by ESWL therapy alone, the factors which influence the number of ESWL shots were analyzed. Stone volume was calculated by summing up the value "length x short axis" for each stone. The value correlated well with the number of shots needed to disintegrate the stone (p less than 0.01). The stones below the pelvis-ureteral junction needed twice shots compared with stones in the pelvis and calyces (80.3: 40.2, p less than 0.005). Stones formed by a single component of cystine or calcium oxalate were hard to be disintegrated (53.2: 31.6, compared with other complex stones). The radiological figure could not predict the fragility.