Restricting living-donor-cadaver-donor exchanges to ensure that standard blood type O wait-list candidates benefit.

Region 1 of the United Network for Organ Sharing created a consortium that allows a person waiting for a kidney transplant to take a higher priority on the list when a relative makes a living donation to another waiting recipient. This can be done by exchanging kidneys between two living-donor-recipient pairs (living paired exchange) or by exchanging kidneys through a living-donor-cadaver-donor exchange (list paired exchange). In this article, the authors argue that a list paired exchange that allows ABO-incompatible donor-recipient pairs to participate is morally problematic because it harms standard blood type O wait-list candidates who already have the longest waiting times. We propose and model restrictions on who can participate in such exchanges to ensure that the standard blood type O wait-list candidates are made better off. We restrict list paired exchanges to (1) ABO-incompatibilities between living donors and recipients for potential recipients with blood types A, B, and AB; and (2) all recipients who have an ABO-compatible, positive-crossmatch living donor. Although these restrictions do not allow for the maximization of the number of organs potentially procured by means of list paired exchanges, they increase the number of kidneys available in an ethically fair manner.