This review article defines the term marginal (suboptimal) donor of organs and there is a summary of current opinions on the importance of protocol biopsies of kidneys performed in these donors during graft collection. Bioptic examination of kidneys in marginal donors provides information that cannot be obtained in any other way. Most authors engaged in this problem hold the view that evaluation of the extent of involution changes and the decision about the appropriateness of the organ for transplantation cannot be based only on the age criteria and there should always be a biopsy performed in suboptimal donors. Histological examination enables an objective evaluation of a pre-existing morphological lesion; especially the extent of glomerulosclerosis, interstitial fibrosis and vascular damage that may limit the functional level and vitality of the graft. As marginal are usually considered kidneys with more than 20% of glomerulosclerosis, kidneys with interstitial fibrosis affecting more than 25% of cortex or kidneys with a finding of arteriosclerotic changes causing more than 25% obliteration of the vascular lumen. It has to be considered, during a transplantation of a marginal kidney, that a long-term survival of the graft will be significantly decreased. But because the number of patients waiting for transplantation is increasing faster than the number of transplants performed, there are possibilities mentioned briefly in this article advising how to optimally use these marginal kidneys as well.

Keywords: Kidney Transplant, Marginal Donor, Protocol Biopsy, Glomerulosclerosis, Interstitial Fibrosis, graft function, Graft Survival