Abdominal Radiograph and Renal Ultrasound Versus Excretory Urography in the Evaluation of Asymptomatic Patients after Extracorporeal Shock Wave Lithotripsy

Abstract

A prospective study was done to compare the relative efficacy of an abdominal radiograph and renal ultrasound to excretory urography for the evaluation of asymptomatic patients 1 month after extracorporeal shock wave lithotripsy.We evaluated 101 renal units in 84 asymptomatic patients who had undergone extracorporeal shock wave lithotripsy 1 month previously with abdominal radiography, excretory urography and ultrasonography to evaluate the presence of retained stone fragments, dilatation of the collecting system and intrarenal or perirenal fluid collections or masses. The combination of abdominal radiography and ultrasonography identified retained fragments in 62 renal units, while excretory urography identified them in 54. Ultrasonography was less specific in identifying dilatation of part or all of the collecting system; proving falsely positive in 7 renal units and falsely negative in 14 compared to excretory urography. However, the case of obstruction was diagnosed correctly by both modalities. Finally, ultrasound appeared to be more specific and more sensitive in the evaluation of the presence of intrarenal or perirenal abnormalities.We conclude that a combination of abdominal radiography and ultrasonography is as good or better than excretory urography in identifying residual stone fragments and intrarenal or perirenal abnormalities. However, the finding of dilatation of all or part of the collecting system by ultrasonography is nonspecific and probably is better evaluated by excretory urography. We suggest that the routine radiological evaluation of asymptomatic patients 1 month after extracorporeal shock wave lithotripsy could be limited routinely to abdominal radiography and ultrasonography. However, when abnormalities of the collecting system are visualized on these studies excretory urography should be performed.