How we match organs
How does UNOS save lives?
United Network for Organ Sharing provides a vital link in the organ transplant process. Its policies and computerized network match donated organs with transplant candidates in ways that save as many lives as possible and provide transplant recipients with the best possible chance of long-term survival.
The matching criteria developed by the transplant community, and approved by the OPTN Board of Directors, are programmed into UNOS’ computer matching system. Only medical and logistical factors are used in organ matching. Personal or social characteristics such as celebrity status, income or insurance coverage play no role in transplant priority.
Prioritizing patients for transplantation
Many factors used to match organs with patients in need are the same for all organs:
The first step
Before an organ is allocated, all transplant candidates on the waiting list that are incompatible with the donor because of blood type, height, weight and other medical factors are automatically screened from any potential matches. Then, UNOS’ computer system determines the order that the other candidates will receive offers.
Geography plays a part
Organ transplants are most successful when preservation and transport time are short. The matching system considers the distance between donor and transplant hospitals. In general, local candidates get organ offers before those listed at more distant hospitals.
The right-sized organ
Proper organ size is critical to a successful transplant, which means that children often respond better to child-sized organs. Although pediatric candidates have their own unique scoring system, children essentially are first in line for other children’s organs.
Factors in organ allocation
Blood type and other medical factors weigh into the allocation of every donated organ, but each organ type has its own individual distribution policy, which reflect factors that are unique to each organ type:
Kidney
- Waiting time
- Donor/recipient immune system compatibility (CPRA score)
- Prior living donor
- Distance from donor hospital
- Survival benefit
- Pediatric status
Lung
- Medical urgency
- Likelihood of survival within 5 years post transplant
- Immune system matching (CPRA)
- Height match
- Blood type
- Pediatric status
- Living donor status
- Travel efficiency
- Proximity efficiency
Liver
- Medical urgency
- Distance from donor hospital
- Pediatric status
Heart
- Medical urgency
- Distance from donor hospital
- Pediatric status
How organ matching works
When a transplant hospital accepts a person as a transplant candidate, it enters medical data—information such as the person’s blood type and medical urgency and the location of the transplant hospital—about that candidate into UNOS’ computerized network. When an organ procurement organization gets consent for an organ donor, it also enters medical data—information such as the donor’s blood type and body size and the location of the donor hospital—into UNOS’ network.
Using the combination of donor and candidate information, the UNOS computer system generates a “match run,” a rank-order list of candidates to be offered each organ. This match is unique to each donor and each organ. The candidates who will appear highest in the ranking are those who are in most urgent need of the transplant, and/or those most likely to have the best chance of survival if transplanted.
The UNOS Organ Center helps place donated organs for transplantation 24 hours a day, 365 days a year.
2022 transplants
42,888
January - December 2022 as of 03/02/2023
See waiting list total and more data and trends
Preserving organs
Donated organs require special methods of preservation to keep them viable after procurement, during transportation and before transplantation. Common maximum organ preservation times include:
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