Percutaneous needle biopsies of renal allografts: the relationship between morphological changes present in biopsies and subsequent allograft function.

In the Cambridge renal transplant unit percutaneous needle biopsies of renal transplants have been extensively used to help identify the cause of impaired allograft function. During the period 1966--1973, 154 of the 269 renal allografts transplanted were biopsied at least once during the first 90 days after transplantation. In this survey the relationship between morphological changes in these biopsy specimens and allograft function 1, 3 and 5 years after transplantation is assessed. A highly significant direct relationship exists between early graft failure and the presence of medial necrosis of arteries, acute glomerular lesions and interstitial haemorrhage. Less than 10% of grafts with one or more of these changes and none in which all three types of lesion were present were capable of supporting life at 1 year. There is a significant association between poor subsequent graft function and mononuclear cell infiltration of the intima of arteries. No clear relationship exists, however, between the function of grafts at 1 and 3 years and the degree of mononuclear cell infiltration of the interstitial tissue. Tubular necrosis was frequently observed and future graft performance is related to the extent and cause of the tubular damage.