Medical transplantation

Medical Transplantation, transfer of a living tissue or organ to an injured or ill person to restore health or reduce disability. Over the past 45 years, surgeons have made great strides in their ability to implant organs in people who are seriously ill. At least 21 different organs—such as hearts, livers, and kidneys—and tissues—such as corneas and bone marrow—can now be successfully transplanted into patients who can then expect to survive for years or even decades.

Each year, more than 20,000 internal organs are successfully implanted into patients in the United States and more than 1,600 organ transplants are performed in Canada. Improved surgical techniques are partly responsible for the success of organ transplants, but a more important factor is the development of drugs that can suppress the body’s rejection of the implanted organ without also leaving the patient highly susceptible to infections.

But this success also created a major problem: as the demand for organs grew, it soon outstripped the supply of donated organs. As of April 2001, more than 76,000 Americans were on a waiting list for organs or tissues and as of December 2000, more than 3,540 Canadians were also on a waiting list.

Each year in the United States, more than 4,000 die before a donated organ can be found. In order to match the scarce supply of donated organs with critically ill patients, in 1984 the United States Congress passed the National Organ Transplant Act to regulate the transplant business. The United Network for Organ Sharing (UNOS) serves as the umbrella organization for organ procurement and transplantation centers around the nation.

When a physician determines that a patient requires a transplant, the patient’s medical information is sent to the closest transplant center. At the transplant center, candidates are evaluated and ranked according to medical criteria. The patient’s medical records are then sent to UNOS for inclusion on its computerized waiting list.

When a donated organ becomes available, it is offered to patients on a waiting list in the donor’s local area. A match is made if laboratory tests show that the recipient is compatible with the available organ, reducing the risk that the organ will be rejected, and if the patient is healthy enough and available to undergo major surgery immediately. If the highest-ranked patient on the list does not meet these criteria, the organ is offered to the next patient on the list. If no one locally can use the organ, it is offered regionally. If it cannot be used regionally, in rare cases the organ is offered to the highest-ranking patient elsewhere in the United States.

In some cases, this system of organ allocation means that people living in certain areas of the country who require a transplant receive a donor organ faster than people living in other areas of the country. To make organ allocation more equitable, in early 2000 the U.S. Department of Health and Human Services (HHS) proposed legislation that called for enhanced government oversight of organ allocation policies. If enacted, the legislation would establish guidelines ensuring that a donated organ or tissue is offered to the patient in most need, no matter where the patient lives.

Most transplanted organs are from people who have died recently, particularly people involved in accidents injuring the head. Once all brain activity stops in a patient, the person is considered legally dead. When the brain dies, the rest of the body is kept alive temporarily until organs can be removed. Someone from either the hospital staff or a local organ procurement organization asks the victim’s family for permission to harvest the organs. To save time and increase the supply of organs, many states encourage people to sign and carry donor cards that indicate their willingness to donate their organs in the event of an accidental death. This information can also be displayed on the driver’s license in many states.

Some organs and tissues can be donated from living donors. For example, millions of people each year donate blood. After donating about 500 ml (about 1 pt) of blood, the donor’s body quickly grows new blood cells to replace the donated ones. The donor suffers no ill effects of donating blood. Other organs that can come from living donors include the kidney and the liver.