The role of ultrasound in the diagnosis of kidney allograft rejection.

Seventeen nephrectomized dogs underwent kidney transplantation from unrelated donors. Routine immunosuppressive therapy was administered. Serial ultrasound studies and biopsies and complete pathological examinations were performed and compared. A number of sonographic changes were observed within the renal parenchyma during rejection, some of which were present before a significant rise in serum creatinine levels. The medulla became enlarged due to edema, followed by growth of the rest of the kidney and thickening of the cortex. The cortical echoes became more sparsely distributed and either increased or decreased in amplitude; distribution was generalized or localized. During rejection, the corticomedullary boundary became indistinct. Later, a decrease in the renal sinus echoes was also noted. In 2 cases, perirenal fluid collections occurred as the result of renal rupture.