Making Procurement Biopsies Important Again for Kidney Transplant Allocation.

Results of procurement biopsies often drive the decision to discard kidneys from deceased donors with advanced age or comorbidities. However, the criteria to perform, process, and score procurement graft biopsies are not standardized. Subject of Review: A recent retrospective, single-center study by Carpenter et al. [Clin J Am Soc Nephrol 2018; 13: 1876-1885] compared the scores obtained from 270 consecutive frozen kidney sections of biopsies at time of procurement with those of paraffin-embedded sections of biopsies at reperfusion and the correlation of both biopsy scores with graft survival. In 116 kidneys, procurement biopsies were repeated, allowing to test the reproducibility of this technique. Procurement biopsies were poorly reproducible, did not correlate with scores obtained with paraffin-embedded reperfusion biopsies, and were not significantly associated with transplant outcomes, while reperfusion biopsies provided an excellent prediction of graft survival. Based on these findings, the authors suggest "an urgent need to reexamine the role of procurement biopsies during allocation given their high resource requirements and association with discards." Second Opinion: Carpenter's paper is important because it emphasizes the crucial role of correct histological evaluation of kidney grafts to accurately predict their survival. In this study, procurement biopsies were frozen and read by on-call pathologists, often with no specific training in renal pathology, while reperfusion sections were paraffin embedded and scored by experienced renal pathologists at Columbia University, New York, NY, USA. This methodological difference per se represents an obvious explanation for the poor concordance between the 2 assessments. Use of wedge biopsies in procurement samples versus core-needle samples in reperfusion biopsies may further account for the discrepancies between scores even in seemingly objective measurements, such as the percentage of glomerulosclerosis. Therefore, these data should not mislead us regarding the importance of procurement biopsies to define organ suitability for transplantation. Rather, they should prompt more studies aimed at optimizing the strategies to score these samples properly for optimal organ allocation.