Sonography in the diagnosis of acute renal allograft rejection and cyclosporine nephrotoxicity.

High-resolution real-time sonography was used at the time an allograft biopsy was performed on 58 renal transplant recipients to elucidate the cause of posttransplantation decline in renal function. These procedures were performed within 3 months of transplantation. Fifty-four out of 58 patients were on a cyclosporine-steroid regimen. Acute rejection was diagnosed if one or more of the following findings was present on sonogram: transplant swelling, increased conspicuity of the medullary pyramids, medullary pyramid enlargement, decreased renal-sinus fat, and pelvi-infundibular thickening. Correlation of sonography and histopathologic findings showed that sonography cannot be used independently to diagnose rejection or to distinguish between cyclosporine nephrotoxicity and rejection. A creatinine level of 2.5 mg/dl was then randomly selected as a threshold level to possibly improve the sonographic results, anticipating that above this threshold an abnormal sonogram would invariably be recorded in the presence of rejection. This threshold was not found to be discriminatory. Only at a higher threshold level of creatinine (6.9 mg/dl or more) was there 100% correlation between acute rejection and the presence of abnormal sonographic findings. Furthermore, whereas most patients with four or five abnormal sonographic criteria tended to have acute rejection, this group of patients constituted a minority and, even within this group, sonography was not entirely reliable in detecting transplant rejection.