Background: Nowadays, given the widening gap between organs available and patients on dialysis waitlisted for kidney transplant, many efforts are steered to expand the donor pool. Resorting consistently to marginal organs, clinical, instrumental and histological methods, that will be specific and accurate in assessing the quality of the graft before transplant, might be advisable in order to prevent any complications, helping to state if the graft has to be transplanted as a single or dual kidney or discarded. Our aim is to test indocyanine green angiography for the assessment of microcirculation patency improvement after Hypothermic Perfusion Machine (HMP) re-conditioning in order to contribute to defining graft quality, jointly with pretransplant biopsy findings and renal resistive index assessed at the end of hypothermic perfusion.

Methods: We conducted a prospective cohort study performing indocyanine green fluorescent angiography during back table surgery before and after hypothermic perfusion on all kidneys available for transplantation which required the treatment because retrieved from Extended Criteria Donors (ECDs) or Donors After Cardiac death (DCDs).

Results: From June 2020 to July 2021 we enrolled 5 grafts retrieved from DCDs selected for transplant and treated through HMP. All perfused kidneys showed a significant rise in terms of fluorescence intensity after HMP treatment: four out of five closes to doubling. Furthermore, statistical analysis demonstrated a moderate correlation (r = 0.39727998889383) between fluorescence intensity with the final resistance index scanned at the end of HMP treatment.

Conclusions: Our results establish how fluorescence can be a valid and cost-effective method for evaluating the graft before transplantation, jointly with histology and renal resistive index assessment. Further studies are needed to standardize this technique.