About Organ Allocation

Matching Organs

Under contract with the U.S. Department of Health and Human Services' Health Services & Resources Administration (HRSA), United Network for Organ Sharing (UNOS) maintains a centralized computer network called UNet^SM. Transplant professionals can access this computer network 24 hours a day, seven days a week.

UNet electronically links all transplant hospitals and organ procurement organizations in a secure, real-time environment. Because UNet uses the Internet, it allows access to all these transplant professionals. However, in order to protect the confidential medical data, all users must use have a secure password.

Matching Donor Organs With Transplant Candidates

When a deceased organ donor is identified, a transplant coordinator from an organ procurement organization accesses the UNet system and enters necessary medical information about the donor. The system uses this information to match the medical characteristics of the candidates waiting against those of the donor. The system then generates a ranked list of patients who are suitable to receive each organ. This list is called a "match run." Factors affecting ranking may include:

• tissue match
• blood type
• length of time on the waiting list
• immune status
• distance between the potential recipient and the donor
• degree of medical urgency (for heart, liver, lung and intestines)

The organ is offered to the transplant team of the first person on the list. Often, the top transplant candidate will not get the organ for one of several reasons. When a patient is selected, he or she must be available, healthy enough to undergo major surgery and willing to be transplanted immediately. Also, a laboratory test to measure compatibility between the donor and potential recipient may be necessary. If the organ is refused for any reason, the transplant hospital of the next patient on the list is contacted. The process continues until a match is made. Once a patient is selected and contacted and all testing is complete, surgery is scheduled and the transplant takes place.

The Five Steps of the Matching Process

1. An organ is donated. When the organ becomes available, the OPO managing the donor sends information to UNOS. The OPO procurement team reports medical and genetic information, including organ size, and condition, blood type and tissue type by entering this information into UNet.
2. UNOS generates a list of potential recipients. The UNOS computer generates a list of potential transplant candidates who have medical and biologic profiles compatible with the donor. The computer ranks candidates by this biologic information, as well as clinical characteristics and time spent on the waiting list.
3. The transplant center is notified of an available organ. Organ placement specialists at the OPO or the UNOS Organ Center contact the centers whose patients appear on the local list.
4. The transplant team considers the organ for the patient. When the team is offered an organ, it bases its acceptance or refusal of the organ upon established medical criteria, organ condition, candidate condition, staff and patient availability and organ transportation. By policy, the transplant team has only one hour to make its decision.
5. The organ is accepted or declined. If the organ is not accepted, the OPO continues to offer it for patients at other centers until it is placed.

Team Involvement

• The UNOS Organ Center: Staffed with organ placement specialists, the UNOS Organ Center coordinates the efforts of many transplant center professionals at the OPO and transplant center with the needs of the patient. It is located in Richmond, Virginia.
• The Organ Donor: This person has died, is compatible with the recipient and meets certain criteria.
• The Transplant Candidate: This person needs a new organ because he or she has suffered from end-stage organ disease. A transplant center has also evaluated this patient, determined that he or she is a candidate for an organ transplant and has added him or her to the national waiting list.
• The Transplant Recipient: A person who has received an organ transplant.
• The Procurement Team: This is a group of professionals who work at an organ procurement organization (OPO) or transplant center and coordinate the recovery of the organ. They remove the organs from the donor's body, so that they can be transplanted.
• The Transplant Team: These are healthcare personnel who perform the transplant operation. They also take care of the patient before, during and after the transplant operation.
• UNet^SM: The secure Internet-based transplant information database created by UNOS. The nation's organ transplant centers and OPOs use it to register patients for transplants, match donated organs to transplant candidates, and manage the critical data of all patients. Transplant professionals can access this computer network 24 hours a day, seven days a week.

Reference and Publication Information

United Network for Organ Sharing (UNOS) is committed to providing accurate and reliable information for transplant patients. The content on this page was originally created on August 1, 2003 by UNOS and last modified on June 4, 2008.

This Web site is intended solely for the purpose of electronically providing the public with general health-related information and convenient access to the data resources. UNOS is not affiliated with any one product nor does UNOS assume responsibility for any error, omissions or other discrepancies.