How the Transplant System Works: Matching Donors and Recipients

Under contract with the U.S. Department of Health and Human Services' Health Services & Resources Administration (HRSA), the United Network for Organ Sharing (UNOS) maintains a centralized computer network linking all organ procurement organizations and transplant centers. This computer network is accessible 24 hours a day, seven days a week, with organ placement specialists in the UNOS Organ Center always available to answer questions.

After being referred by a doctor, a transplant center evaluates the patient. The transplant center runs a number of tests and considers the patient's mental and physical health, as well as his or her social support system. If the center determines that the patient is a transplant candidate, they will add the patient's medical profile to the national patient waiting list for organ transplant. The patient is not placed on a ranked list at that time. Rather, the patient's name is added to the "pool" of patients waiting.

When a deceased organ donor is identified, a transplant coordinator from an organ procurement organization accesses the UNOS computer. Each patient in the "pool" is matched by the computer against the donor characteristics. The computer then generates a ranked list of patients for each organ that is procured from that donor in ranked order according to organ allocation policies. Factors affecting ranking may include tissue match, blood type, length of time on the waiting list, immune status and the distance between the potential recipient and the donor. For heart, liver, and intestines, the potential recipient's degree of medical urgency is also considered. Therefore, the computer generates a differently ranked list of patients for each donor organ matched.

The organ is offered to the transplant team of the first person on the list. Often, the top patient 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 recipient may be necessary. For example, patients with high antibody levels often prove incompatible to the donor organ and cannot receive the organ because the patient's immune system would reject it.

Once a patient is selected and contacted and all testing is complete, surgery is scheduled and the transplant takes place.

Related Internet Sites

U.S. Department of Health and Human Services Web site for Organ Donation
www.organdonor.gov

The Organ Procurement and Transplantation Network
Operated by UNOS under contract with HRSA.
http://optn.transplant.hrsa.gov/

Last updated: April 15, 2009