Prospective study of the effects of shock wave lithotripsy on renal function: role of post-shock wave lithotripsy obstruction

Abstract

ObjectivesTo examine the effects of transient post-shock wave lithotripsy (SWL) obstruction on renal function after SWL application for treatment of renal stones in nonobstructed kidneys. MethodsOne hundred consecutive patients with unilateral renal stones were treated by SWL monotherapy. They had a normal laboratory profile and no or controlled urinary tract infection. The urinary tract was radiologically normal. Technetium-99m mercaptoacetyltriglycine and Doppler ultrasonography were performed for all cases a few days before and 1 week and 3 months after SWL. Renal uptake, time to peak clearance, split renal function, effective renal plasma flow, and resistive index were obtained. Patients were stratified into two groups. Group 1 consisted of patients with normal kidneys before SWL and unobstructed kidneys after SWL (n = 84). Group 2 consisted of patients with normal kidneys before SWL that were obstructed 1 week after SWL (n = 16). ResultsIn group 1, there was a gradual increase in the effective renal plasma flow that became significant after 3 months, up to 114% of the pretreatment levels (P = 0.008). The glomerular filtration rate was stable 1 week after SWL and had increased significantly after 3 months, up to 110% of the pretreatment levels (P = 0.006). In group 2, there was marked deterioration of the effective renal plasma flow and glomerular flow rate to 50.5% (P = 0.002) and 45.8% (P = 0.001), respectively, of the pretreatment levels. These levels returned to the basal levels after 3 months. No significant changes occurred in the resistive index in both groups. ConclusionsExtracorporeal shock wave lithotripsy has no deleterious effects on the renal function. Post-SWL obstruction, although transient, has a major effect on the renal function on the treated side and must be managed urgently.