Kidney and pancreas lists are based on location, blood type, Human Leukocyte Antigen (HLA) typing and wait time. When a recipient for a kidney or pancreas has no direct antibodies to the donor HLA the match is said to be a 0 ABDR mismatch or zero antigen mismatch. A zero mismatch organ has a low rate of rejection and allows a recipient to be on lower doses of immunosuppressive drugs. Since zero mismatches have such high graft survival these recipients are afforded priority regardless of location and wait time. UNOS has in place a "Payback" system to balance organs that are sent out of a DSA because of a zero mismatch. Location of a transplant center with respect to a donor hospital is given priority due to the effects of Cold Ischemic Time (CIT). Once the organ is removed from the donor, blood no longer perfuses through the vessels and begins to starve the cells of oxygen (ischemia). Each organ tolerates different ischemic times. Hearts and lungs need to be transplanted within 4–6 hours from recovery, liver about 8–10 hours and pancreas about 15 hours; kidneys are the most resilient to ischemia. Kidneys packaged on ice can be successfully transplanted 24–36 hours after recovery. Developments in kidney preservation have yielded a device that pumps cold preservation solution through the kidneys vessels to prevent Delayed Graft Function (DGF) due to ischemia. Perfusion devices, often called kidney pumps, can extend graft survival to 36–48 hours post recovery for kidneys.
One historical example of a private organization using this model is LifeSharers, which is free to join and whose members agree to sign a document giving preferred access to their organs. "The proposal [for an organ mutual insurance pool] can be easily summarized: An individual would receive priority for any needed transplant if that individual agrees that his or her organs will be available to other members of the insurance pool in the event of his or her death. … The main purpose [of this proposal] is to increase the supply of transplantable organs in order to save or improve more lives." Technical advances allows the use of donors that were previously rejected. For example, hepatitis C can be knowingly transplanted and treated in the organ recipient.In hospitals, organ network representatives routinely screen patient records to identify potential donors shortly in advance of their deaths. In many cases, organ-procurement representatives will request screening tests (such as blood typing) or organ-preserving drugs (such as blood pressure drugs) to keep potential donors organs viable until their suitability for transplants can be determined and family consent (if needed) can be obtained. This practice increases transplant efficiency, as potential donors who are unsuitable due to infection or other causes are removed from consideration before their deaths, and decreases the avoidable loss of organs. It may also benefit families indirectly, as the families of unsuitable donors are not approached to discuss organ donation. Distribution
The United States has two agencies that govern organ procurement and distribution within the country.