UNOS is a private, non-profit corporation and a federal contractor with OPTN. Under this contract, "UNOS maintains a computer-assisted organ allocation system and an Organ Center, which allows 24-hour transplant program access to the donor/recipient matching system," as well as the Scientific Registry of Transplant Recipients (HRSA, on-line source).
Under the current system, a patient is placed on the UNOS waiting list after certain criteria have been met. First, the patient's physician must determine that an organ transplant may be necessary. Then the patient is referred to a transplant center for evaluation, where "[t]he medical team at the center considers the patient's past and present medical condition as well as a variety of psychosocial factors, such as a history of complying with past medical directives and having sufficient emotional support from family or friends" (UNOS, on-line source). UNOS describes the process as follows:
When a patient is added to the transplant waiting list, his or her medical profile is entered in the UNOS computer. The computer adds the patient's name to a 'pool' of patient names. When an organ donor becomes available, all patients in the pool are compared to that particular donor. The computer then generates a list of patients ranked in order based on biological compatibility and medical criteria. The organs are distributed first locally. If no suitable match exists in that area, the organ is offered regionally, then nationally.
Donor-recipient matches are based on many criteria, including medical urgency of the transplant candidate, time spent on the waiting list, biologic compatibility between the donor and the recipient (such as organ size, blood type, and genetic makeup) and the candidate's ability to be transplanted immediately. (UNOS, on-line source)