Frozen section evaluation of preimplantation donor kidneys: Application of the Maryland aggregate pathology index

The benefits of renal transplantation for patients with end-stage renal disease on hemodialysis are well established, but currently there is a significant shortage of organs available for transplantation. In an effort to increase the size of the donor pool, donors that may have been excluded from donating previously are currently accepted. Frozen section evaluation of preimplantation donor kidney biopsies is particularly important for organs from these expanded criteria donors, both to determine organ suitability and as a tool to predict short- and long-term graft survival. Although significant progress has been made in the field, controversy still remains regarding the predictive value of the individual pathologic parameters to predict graft outcome. The Maryland Aggregate Pathology Index score is based on the identification of 5 histologic parameters and is used to stratify donor organs into low-, intermediate-, and high-risk groups, which correlate with overall graft survival. Irrespectively of the transplant donor population, preimplantation donor kidney frozen section evaluation is an invaluable tool for optimal use of the available organs.