Morphological and functional changes in canine kidneys following extracorporeal shock-wave treatment

Extracorporeal shock-wave lithotripsy (ESWL) has rapidly become established worldwide as a routine method for treatment of nephro- and ureterolithiasis. Although initial studies showed no tissue-damaging effect by the shock waves, we found, in an animal experiment using canine kidneys, that the ESWL-induced damage to the renal parenchyma is more marked than originally assumed. The damage is limited to the area that was focused on, and heals relatively rapidly by connective tissue encapsulation with final cicatrisation without any further residual effects being observed up to the present. This parenchymal damage is probably also the cause of the macrohematuria that is always observed during therapy. The resulting tissue damage is not extensive enough to cause a demonstrable reduction of function as measured by the usual methods (serum creatinine, creatinine clearance, isotopy renography, i.v. urography). In serum we observed a transient decrease of calcium, an immediate increase of lactate-dehydrogenase, transaminases (SGOT and SGPT) and a delayed increase of alkaline phosphates. Creatinine, blood urea nitrogen, sodium, potassium and amylase remained within normal limits. In urine, a decrease of creatinine and an increase of glucose excretion were noted. We believe that these changes represent a relatively mild and transient damage of renal cells and do not reflect the occasionally heavy morphological changes observed after shock-wave exposure. The main clinical complication is the large subcapsular hematoma which, according to the present knowledge, could well result from a lesion of the larger peripheral vessels. Damage to other organs such as subserous colonic and small bowel hematomata are to be expected although they do not lead to clinical symptoms.