The efficacy of extracorporeal shock wave lithotripsy for isolated lower pole calculi compared with isolated middle and upper caliceal calculi.
PURPOSE: We assess the efficacy of extracorporeal shock wave lithotripsy monotherapy for isolated lower pole nephrolithiasis, and compare it to that for isolated middle and upper caliceal calculi. MATERIALS AND METHODS: We treated 714 renal units in 687 patients with isolated caliceal stones using a Lithostar lithotriptor (Siemens Medical Systems, Erlangen, Germany). The stones were localized in the lower, mid and upper calices in 455, 104 and 128 patients, respectively. Stone load was recorded in cm.2. Patients were stratified into 3 groups based on stone burden. The energy and shock waves, use of anesthesia, number of treatment sessions, auxiliary measures and complications were noted. Patients were evaluated with intravenous urogram or plain film of kidneys, ureters and bladder, and ultrasonography when stone-free, or clinically significant residual fragment status, including nonobstructive and noninfectious insignificant fragments 4 mm. or less, was noted at the fluoroscopic control 2 to 4 weeks after the last session. Final clinically significant residual fragment decision was made 10 to 12 weeks after the last session. Extracorporeal shock wave lithotripsy was considered a failure if no fragmentation was noted after session 3 and continued if fragmentation was noted. Results regarding caliceal localization were compared. RESULTS: Complete data were available on 591 renal units. Auxiliary procedures were used in 81 (14%) units before treatment. Anesthesia was given to 101 (17%) patients. The mean number of shock waves and energy used were 2,022 and 17.4 kV., respectively. The difference in shock wave, energy and treatment rate among 3 caliceal locations reached statistical significance only for energy delivered to the lower and upper calices. The effectiveness quotient of extracorporeal shock wave lithotripsy was 36%, 46% and 41% for lower, middle and upper pole stone disease, respectively (p = 0.4). There was a highly significant correlation between stone-free and re-treatment rates, and stone burden. The overall stone-free rate was 66%, and 63%, 73% and 71% for lower, middle and upper caliceal stones, respectively (p = 0.1). For the group with stones greater than 2 cm.2 overall stone-free rate decreased to 49%, and 53%, 60% and 23% in lower, middle and upper caliceal locations, respectively. Overall, extracorporeal shock wave lithotripsy monotherapy failed in 46 (7.7%) renal units. Steinstrasse developed in 39 (6.5%) patients who were then treated with repeat lithotripsy. CONCLUSIONS: Extracorporeal shock wave lithotripsy appears to be successful for management of isolated caliceal stone disease. Treatment efficacy was not significantly different among stones localized in lower, middle and upper poles. We recommend it as the primary treatment of choice for stones less than 2.0 cm.2 in all caliceal locations. Treatment should be individualized for management of caliceal stones greater than 2.0 cm.2 until large prospective randomized trials comparing shock wave lithotripsy and percutaneous nephrolithotomy are available.