Preimplantation Histopathologic Assessment of Deceased Donor Kidneys: Recommendations from the Banff Time-Zero Biopsy Working Group.

Transplantation using kidneys from deceased donors with marginal clinical characteristics is increasing to maximize access to transplant. Preimplantation biopsies of such kidneys are often obtained to determine the degree of chronic changes as an objective supplement to donor clinical based assessment of organ quality, particularly in the United States. There is conflicting evidence and heterogenous practice about how preimplantation biopsies should be performed, interpreted, and incorporated into organ disposition decisions. In 2022, The Banff Foundation for Allograft Pathology tasked its Time-Zero Biopsy Working Group with reviewing existing literature on preimplantation biopsies to prepare consensus recommendations on situations in which these biopsies should be performed and suggest best practices for improving reproducibility of biopsy readings. This workgroup report tabulates the Working Group's recommendations and identifies gaps that need to be filled to advance preimplantation biopsy clinical practice in donor selection. The major recommendations are that a preimplantation biopsy should only be performed when clinical assessment tools indicate that the kidney is unsuitable for utilization, that the clinical and preimplantation biopsy findings should be interpreted together for organ utilization decisions, and that digital whole slide images be promoted to facilitate setting up reporting networks of nephropathologists. Additional prospective studies using predictive modeling approaches are needed to optimize preimplantation biopsy criteria, sampling, interpretation, and incorporation into kidney allocation decisions.