The diagnosis of humoral liver allograft rejection is difficult to establish with certainty, and is often one of exclusion, where other causes injury are reasonably excluded. Therefore, it is important establish that the donor liver was normal at the time of implantation. This is most often accomplished by a "backtable" biopsy, taken after harvesting, but before implantation into the recipient. In this biopsy, note the intact lobular architecture, and absence of significant pathological changes.