MECHANICAL PERCUSSION, INVERSION AND DIURESIS FOR RESIDUAL LOWER POLE FRAGMENTS AFTER SHOCK WAVE LITHOTRIPSY: A PROSPECTIVE, SINGLE BLIND, RANDOMIZED CONTROLLED TRIAL

PURPOSE: We compare the effectiveness of mechanical percussion and inversion with observation for eliminating lower caliceal fragments 3 months after shock wave lithotripsy. MATERIALS AND METHODS: At 3 months after shock wave lithotripsy 69 patients with residual lower caliceal fragments 4 mm. or less were randomized to receive either mechanical percussion and inversion or observation for 1 month. The observation group then received crossover mechanical percussion and inversion if fragments persisted. All patients were followed with plain film of the kidneys, ureters and bladder to assess the stone area and stone-free status, and renal tomography or noncontrast spiral computerized tomography to confirm stone-free status. A blinded radiologist reviewed all films. Patients were treated with a mechanical chest percussor applied to the flank while inverted to greater than 60 degrees after receiving 20 mg. furosemide. RESULTS: A total of 35 patients were randomized to receive immediate mechanical percussion and inversion therapy and 34 observation. Of the patients in the observation group 28 subsequently received mechanical percussion and inversion after completing the observation period. The groups were not different in gender, body mass index, side affected, stone location or renal anatomical features. The mechanical percussion and inversion group had a substantially higher stone-free rate than the observation group (40% versus 3%, respectively, p <0.001). The mechanical percussion and inversion group also had a greater improvement in total stone area than controls (-63.3% versus +2.7%, respectively, p <0.001). No significant adverse effects were noted in the mechanical percussion and inversion group. CONCLUSIONS: Mechanical percussion and inversion is a safe and effective treatment option for residual lower caliceal fragments 3 months after shock wave lithotripsy. Nearly 50% of patients become stone-free, and stone burden is decreased by 50% in the remainder.