How Are Transplant Recipients Matched With Donors?

The process of matching donors with transplant recipients is complex and contains many factors and “moving parts.” Considerations include:

• Which organs are available for transplantation
• Physical compatibility (blood type, height, weight and age)
• The location of the donor and recipient
• Medical urgency

According to the Department of Health and Human Services, the matching process begins when the regional organ procurement network is notified that a potential donor has died. While the medical team at the hospital continues efforts to preserve the organs through artificial means such as ventilator support, intravenous fluids and medicine to maintain blood pressure, the OPO enters the patient’s information into The Organ Procurement and Transplantation Network (OPTN) database, which operates on a set of nationally established rules. The computer system determines where and to whom each organ goes. Although the decision-making process is far from simple, the basic steps include the following:

• Eliminate all unsuitable candidates: The computer first eliminates any candidate who is an unsuitable recipient for any or all available organs due to blood type, age, height or weight. 
• Prioritize by region: For the purposes of organ allocation, the U.S. is divided into 57 local Donation Service Areas and 11 regions. For all organs except hearts and lungs, organs are allocated first to the sickest patients in the region where the donor is located. If there is more than one potential recipient in equal medical need of a transplant in the region, the patient located in the same local Donation Service Area as the donor usually gets first dibs. If there is no potential recipient in the region, the search expands to the entire country.
  • Hearts and lungs: Because hearts and lungs must be transplanted quickly after retrieval, they are allocated according to distance from the donor hospital versus by region. 
• Consider size and age:  Pediatric patients are generally prioritized over adults when an available organ is from a child. If there is no child on the waiting list, a pediatric organ may go to an adult. 
• Other medical factors: In addition to blood type and medical urgency, the matching system uses a number of factors in determining the appropriate donor-recipient match. Many of these are specific to the organ involved.
  • Kidney
    • Time on waiting list
    • Tissue compatibility (based on immune system markers)
    • Pediatric status
    • Prior living donation (patient had a kidney transplant from a living donor that failed)
    • Distance from donor hospital
    • Survival benefit
  • Heart
    • Medical urgency
    • Distance from donor hospital
  • Lung
    • Survival benefit
    • Medical urgency
    • Time of the waiting list
    • Distance from donor hospital
  • Liver
    • Medical need
    • Distance from donor hospital 

Organs are preserved to ensure their viability. However, the time between organ retrieval and transplantation is limited. In general, the maximum survival time for preserved organs is:

• Heart, lung — 4-6 hours
• Liver — 8-12 hours
• Pancreas — 12-18 hours
• Kidney — 24-36 hours

Sadly, an inordinate number of retrieved organs do not reach their destination in time due to what experts call an antiquated system that sends life-saving organs cross-country as cargo on commercial airlines. According to an NBC News report based on an investigation by Kaiser Health News and Reveal from the Center for Investigative Reporting, between 2014 and 2019, 170 organs were discarded because of flight delays.

Sources

“Lost luggage: How lifesaving organs for transplant go missing in transit”. NBS News. https://www.nbcnews.com/health/health-news/lost-luggage-how-lifesaving-organs-transplant-go-missing-transit-n1130891 

“Organ Procurement and Transplantation Network Policies and Reports”. HRSA. https://www.organdonor.gov/about-us/legislation-policy/optn 

“How organ allocation works”. OPTN. https://optn.transplant.hrsa.gov/patients/about-transplantation/how-organ-allocation-works/