Sonographic evaluation of renal stones treated by extracorporeal shock-wave lithotripsy

Real-time sonography was performed on 94 patients the day before and at 24 and 48 hr after extracorporeal shock-wave lithotripsy (ESWL) therapy. The ability of sonography to detect renal stones before ESWL, changes in the calculi after ESWL, and the occurrence of pre- and post-ESWL hydronephrosis was evaluated. Abdominal radiographs and linear renal tomography were used as the standard of comparison. Six other patients had sonography only either before or after ESWL. One hundred patients had a total 105 kidneys treated; 18 kidneys with more than three stones were not included. The other 87 kidneys had 102 stones evaluated by sonography before having ESWL; 66 stones (65%) were identified and 36 were not. Of those calculi not seen, 10 were less than or equal to 5 mm in diameter. Nineteen of the other 26 stones were in the ureter or at the ureteropelvic junction. Comparison of sonograms of 80 kidneys obtained before and after ESWL revealed no change in 37 (46%), more stones or fragments detected in 23 (29%), fewer stones or a change in location in 12 (15%), and an apparent decrease in the size of the original stone in eight (10%). Hydronephrosis was detected by pre-ESWL sonography in 16 kidneys (20%) and was noted to develop after ESWL in 20 (31%) of the 64 other kidneys. These results indicate that the ability of sonography to detect renal calculi is related not only to stone size but also to location. The clinical significance of pre- and post-ESWL hydronephrosis found by sonography must be considered in conjunction with the patient's symptoms, laboratory data, and other radiographic studies. Therefore, the routine use of sonography in the post-ESWL patient does not seem warranted.