Frozen section evaluation of deceased donor kidney biopsies: A field guide

The demand for donated kidneys is steadily increasing, making it critical that the transplant community maximizes the use of organs procured from deceased donors. When a donated kidney becomes available, a transplant program evaluates the suitability of the organ for their patients and will choose whether to decline or accept. A pre-implantation biopsy may be performed if the transplant center is unsure about the suitability of the organ. More than half of deceased donor kidneys are biopsied prior to implantation, and "biopsy findings" is the most commonly cited reason for a kidney not being accepted for transplantation. This is despite the fact that retrospective analyses at multiple centers have revealed that the results of kidney pre-implantation biopsies are poorly reproducible, inaccurate, and do not correlate with clinical outcomes. A prospective study comparing the scores of paraffin-embedded pre-implantation biopsies given by on-call pathologists to scores given by experienced renal pathologists found that only the evaluation by the renal pathologist was significantly associated with graft function and survival. In 2023, the Organ Procurement and Transplantation Network implemented the Standardized Kidney Biopsy Reporting and Data Collection policy, specifying how kidney pre-implantation biopsies should be scored and reported. This article aims to increase awareness of the reporting criteria for kidney pre-implantation biopsies, thereby increasing the accuracy and reproducibility of the results and decreasing the number of deceased donor kidneys that are inappropriately discarded.