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The world of organ donation and transplantation has a language all its own. There are many terms and topics that you may not have heard of before. Get to know what it all means by selecting the letters below or just scrolling down.

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The process of determining how organs are distributed. Allocation includes the system of policies and guidelines which ensure that organs are distributed in an equitable, ethical and medically sound manner.


An allograft is a transplant of an organ or tissue that comes from another person of the same species.


An aneurysm or aneurism is a ballooning or weakened area in the wall of a blood vessel. As it increases in size, the risk of rupture increases, which can lead to internal bleeding and death.

Anti-Rejection Medicine (immunosuppressive drugs)

Medicines that reduce or prevent the body's ability to reject a transplanted organ or tissue.


A protein substance made by the body's immune system to attack a foreign substance, for example, a blood transfusion, virus or pregnancy. Because antibodies attack transplanted organs, transplant patients must take powerful drugs to reduce the body's attack on the transplanted organ. See anti-rejection medicine.


A foreign substance, such as a transplanted organ or tissue, that triggers the body to reject it (destroy it.)

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Blood Vessels

The arteries, veins, and capillaries through which blood circulates. Blood vessels can be donated and transplanted.


Dense tissue that forms the skeleton and supports the body. Bone can be donated and transplanted.

Bone Marrow

A thick liquid substance found in the body's hollow bones, such as leg, arm and hip bones. Marrow consists of cells that develop into blood cells (platelets, red blood cells, and white blood cells). Marrow for transplant is usually collected from the pelvic bone.

Brain Death

Brain death occurs when the brain is totally and irreversibly non-functional. Brain death is caused by not enough blood supply of oxygen which causes the brain cells to die.

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Cadaveric Donors

Also called non-living or deceased donors (preferred term), are those who donate their organs or tissue after they have died.


A patient who has been placed on the national waiting list for solid organ transplantation.

Circulatory Death

Occurs when a person's heart stops and cannot be resuscitated. Just like brain death, there is no recovery from circulatory death (also known as cardiac death).

Cold Ischemia Time

The time an organ is without blood circulation and is kept cold—from the time the organ is removed from the donor to the time it is transplanted into the recipient. In surgery, the time between the chilling of a tissue, organ, or body part after its blood supply has been reduced or cut off and the time it is warmed by having its blood supply restored. This can occur while the organ is still in the body or after it is removed from the body if the organ is to be used for transplantation.

Connective Tissue

Forms the supportive and connective structures of the body, such as tendons, ligaments cartilage, bone and fascia (the silver colored covering of muscles). Connective tissue surrounds many organs.


The transparent outer covering of the eye's iris and pupil. Corneas can be donated and transplanted to restore sight for people with damaged corneas.


A blood test performed before a transplant to find out if the specific donor organ to be transplanted is likely to be rejected by the prospective recipient. If the test is positive, the donor and recipient are "incompatible" and the transplant is unlikely to be performed with an organ from that donor.


A medicine that suppresses the body's immune response thereby preventing organ rejection.

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Deceased Donor

A person who has been declared dead and whose organs and/or tissues have been donated for transplantation.

Designated Requestor

Defined in the Centers for Medicare and Medicaid Conditions of Participation as an individual who has completed a course offered or approved by the OPO and designed in conjunction with the tissue and eye bank community in the methodology for approaching potential donor families and requesting organ donation. The interpretation of this rule allows for some degree of flexibility.


The act of giving organ(s), tissue(s), or blood to someone else without compensation.


A mechanical process designed to remove toxic substances from the blood, including correcting the balance of fluids and chemicals in the body and removing wastes when the kidneys are unable to do so. See hemodialysis and peritoneal dialysis.

Domino Transplant

Although it does not happen often, a domino transplant occurs when patient A needs lungs, but the best treatment is to give that patient a heart and lung combination. Since patient A's heart was good, it can be transplanted into patient B who needs only a heart.

Donor Designation

Documentation of an individual’s decision to donate organs, eyes, and/or tissues after death, usually designated on a driver’s license or through a State donor registry.

Donor Registries

A confidential electronic database in which individuals can enter and store their wish to be an organ and tissue donor. Most registries are for a single state, but a few serve more than one state. Most registries have enrollment capacity through the motor vehicle offices and many also have online registry portals. Because registry information is accessible on a 24/7 basis to authorized procurement personnel, it is the safest and quickest way to determine if a deceased individual wanted to be a donor.

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End-Stage Organ Disease

A disease that leads, ultimately, to permanent, complete failure of an organ to function. Some examples are emphysema (lungs), cardiomyopathy (heart), and polycystic kidney disease (kidneys).

End-Stage Renal Disease (ESRD)

The complete or almost complete failure of the kidneys to function. The kidneys can no longer remove wastes, concentrate urine, and regulate many other important body functions.

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First Person Consent Legislation

State laws ensuring legal authority to proceed with organ procurement without consent from the family based on a legal indication of the deceased's consent for donation, such as on a driver's license or other official document.

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Genetic Disorder

A disease or disorder related to heredity, birth or origin.


A transplanted organ or tissue.

Graft Survival

The length of time an organ functions successfully after being transplanted.

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A muscular organ that pumps blood through the body. The heart can be donated and transplanted.

Heart Valves

Prevent the back flow or leakage of blood as it is being pumped through the chambers inside of the heart. Heart valves can be donated and transplanted.


A treatment for kidney failure in which the patient's blood is passed through a filtering membrane to remove excess fluid and wastes.


The examination or testing of antigens to determine if a donor organ will "match" and be compatible with a potential recipient's system. This routine test is often called tissue-typing and helps identify the most suitable recipient for a donated organ.

Human Leukocyte Antigens (HLA)

A genetically determined series of markers (molecules) located on human white blood cells (leukocytes) and on tissues that are inherited from both biological parents. HLA matching is important for compatibility between donor and recipient.

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Relating to an organ being damaged or destroyed by a disease or condition of unknown origin.

Immune Response

The body's natural defense against foreign objects or organisms that invade the body, such as bacteria or transplanted organs.

Immunosuppressive Drugs

Chemical agents that cause the human body not to produce antibodies that normally fight off foreign material in the body. The production of these antibodies needs to be suppressed in order to permit the acceptance of a donor organ by the recipient's body. See also Anti-Rejection Medicine.

The process of reaching a voluntary agreement based on a full disclosure and full understanding of what will take place. Informed consent often refers to the process of making decisions regarding participation in research as well as undergoing medical procedures, including the decision to donate the organs of a loved one.


The portion of the digestive tract extending from the stomach to the anus, consisting of the stomach, the upper segment (small intestine) and lower segment (large intestine.) The intestines can be donated and transplanted.

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A pair of organs that maintain proper water and electrolyte balance, regulate acid-base concentration, and filter metabolic waste which is excreted as urine. Kidneys can be donated by deceased and living donors to be transplanted.

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Fibrous bands or sheets that link two or more bones, cartilages, or structures together. Ligaments provide stability during rest and movement and protect against excessive movements such as hyper-extension or hyper-flexion. Ligaments can be transplanted. See Connective Tissue.


A large reddish-brown organ that secretes bile and is active in the formation of certain blood proteins and in the metabolism of carbohydrates, fats, and proteins. The liver, like the kidneys, assists in the removal of waste and toxins from the blood stream. The liver can be donated by deceased donors, and a liver lobe (section) can be provided by a living donor to be transplanted. The donor's liver will grow to full size, and the transplanted lobe will too.

Living Donor

A person who donates an organ or tissue while alive.


The organs that enable breathing to take place, providing life-sustaining oxygen to the body and its organs. Air is inhaled into the lungs and oxygen in the air is exchanged for carbon dioxide that is then exhaled. The exchange happens in the blood as it circulates through the sponge-like lung tissue. The lungs can be donated and transplanted, and a lung lobe can be donated by a living donor.

Lymphocytotoxic Crossmatch Test

The lymphocytotoxic crossmatch test detects antibodies in the recipient that react with donor HLA antigens prior to transplantation. Lymphocytotoxic crossmatch tests are used primarily for transplant candidates to assess the suitability of a potential donor. A positive lymphocytotoxic crossmatch identifies antibodies responsible for hyperacute rejection of kidney grafts and is therefore a clear contraindication to transplantation.

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The degree of compatibility or likeness between a donor and a recipient.

Match Run

The list that is generated when an organ donor's information is entered into the national waiting list computer system to identify potential recipients.

Metabolic Disorder

A condition or disease related to dysfunction in the chemical processes and activities of the body (i.e., metabolism).

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National Organ Transplant Act (NOTA)

Passed by Congress in 1984, NOTA initiated the development of a national system of organ sharing and a scientific registry to collect and report transplant data. It also outlawed the sale of human organs in the United States.


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A part of the body, made up of various tissues, which performs a particular function. Transplantable organs are: heart, intestines, liver, lungs, kidneys, and pancreas.

Organ Donation

Giving an organ or a part of an organ to be transplanted into another person. Organ donation can occur with a deceased donor, who can give kidneys, pancreas, liver, lungs, heart, intestinal organs, and with a living donor, who can give a kidney or a portion of the liver, lung, or intestine.

Organ Preservation

Methods used to maintain the quality of organs between removal from the donor and transplantation into recipient. These methods include preservation solutions, pumps, and cold storage. Preservation times can vary from 2 to 48 hours depending on the type of organ being preserved. See Cold Ischemia Time.

Organ Procurement and Transplantation Network (OPTN)

In 1984, Congress passed the National Organ Transplant Act that mandated the establishment of the OPTN and Scientific Registry of Transplant Recipients. The purpose of the OPTN is to improve the effectiveness of the nation's organ procurement, donation and transplantation system by increasing the availability of and access to donor organs for patients with end-stage organ failure. The Act stipulated that the network be a nonprofit, private sector entity whose members are all U.S. transplant centers, organ procurement organizations and histocompatibility laboratories. The OPTN is administered by UNOS under contract to the U.S. Department of Health and Human Services.

Organ Procurement Organizations (OPO)

Local organizations throughout the U.S. designated by the Centers for Medicare and Medicaid Services (CMS) are responsible for increasing the number of registered donors in their service areas, and for coordinating the donation process when actual donors become available. OPOs evaluate potential donors, discuss donation with surviving family members, and arrange for the surgical removal and transport of donated organs. To increase donor registration, OPOs implement community outreach strategies to encourage people to sign up in their state donor registry. Find your local OPO

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Long, irregularly shaped gland that lies behind the stomach. Some glands in the pancreas secrete insulin. Pancreas transplants give patients with diabetes a chance to become independent of insulin injections. In addition to insulin, the pancreas secretes digestive enzymes (into the small intestine) that aid in the digestion of proteins, carbohydrates, and fats.

Peritoneal Dialysis

A process of filtering waste using the peritoneal membrane inside the abdomen. The abdomen is filled with special solutions that help remove toxins. The solutions remain in the abdomen for a time and then are drained out. This form of dialysis can be performed at home, but must be done every day.

Peripheral blood stem cells (PBSC)

Peripheral blood stem cells are the cells that make their way from the bone marrow to the circulating blood. Learn more about donating bone marrow or PBSC.


The surgical procedure of removing an organ, corneas or other tissue(s) from a donor. See Recovery.

Procurement Coordinator

Staff member of the OPO, typically a nurse, paramedic or other medically trained individual who is responsible for evaluating potential donors, discussing donation with family members, medically managing the donor prior to the recovery of organs and tissues and arranging for the donation process (removal and transport of donated organs).

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In the context of organ and tissue transplantation, this is the patient receiving the donated organ or tissue.


In the context of organ and tissue transplantation, refers to the process of removing organs and tissues from the donor.

Rejection (Acute and Chronic)

The body's way of protecting itself against a foreign invader such as infectious germs. The body sees the transplanted organ or tissue as a foreign invader and attempts to destroy it. Acute rejection happens very quickly; chronic rejection is the slow failure of a donated organ to function.

Required Request

A law passed in 1986 requiring hospitals to have a policy in place requiring all families of suitable donors to be asked to give consent to their loved one's organs and tissues to be used for transplant. This law is expected to increase the number of donated organs and tissues for transplantation by giving more people the opportunity to donate.


A healthcare professional who discusses organ donation with surviving family members of a potential donor in order to obtain their consent for donation to occur.

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Scientific Registry of Transplant Recipients (SRTR)

In 1984, Congress passed the National Organ Transplant Act (See also National Organ Transplant Act (NOTA) that mandated the establishment of the Organ Procurement and Transplantation Network and SRTR.The purpose of the SRTR is to provide evaluation of clinical information about donors, transplant candidates and recipients, as well as patient and graft survival rates.


This is the largest organ of the body and has several different functions (e.g., protection from infection, fluid balance, cooling). Skin grafts can save the life a burn victim and can provide severely scarred individuals with a better quality of life.


In the context of transplantation, an indication of the degree of medical urgency for patients awaiting heart or liver transplants.

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A tough, flexible band of fibrous tissue that connects muscles to bones. The skeletal muscles move the bones for walking, jumping, lifting, etc. by contracting and pulling the bones. The tendon attaches to the muscle and bone and transmits the force of muscle contraction to the bone. Tendons can be transplanted. See Connective Tissue.


A body part consisting of similar cells that perform a special function. Examples of tissues that can be transplanted are bones, corneas, heart valves, ligaments, veins, and tendons.

Tissue Typing

A procedure in which the tissues of a prospective donor and recipient are tested to identify the human leukocyte antigens (HLA). See HLA.


The transfer of cells (e.g. stem cells), tissue, or organs from one person to another.

Transplantation, Allogenic (allograft)

Transplantation between genetically different members of the same species (not identical twins).

Transplantation, Autologous

Receiving a transplant of one's own cell or tissues. This type of transplantation can be used to repair or replace damaged tissue. For example, autologous bone marrow transplantation permits the use of strong cancer therapies that can damage bone marrow. Bone marrow is removed prior to treatment and once the treatment is completed marrow that has not been affected by the therapy is transplanted back into the patient.

Transplant Coordinator

A transplant center staff member responsible for managing the care and progress of potential transplant recipients before, during and after the transplantation.

Transplant Recipient

A person who has received a tissue or organ transplant.

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United Network for Organ Sharing (UNOS)

The private, nonprofit membership organization that coordinates the national matching system, the OPTN, under contract to the U.S. Department of Health and Human Services. As OPTN contractor, UNOS has established and continually strives to improve tools, systems and quality processes that support OPTN contract objectives and requirements.

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Vascularized Composite Allograft (VCA)

A transplant that is composed of several kinds of tissue such as skin, bone, muscles, blood vessels, nerves, and connective tissue, VCAs include hand, arm, or face transplants.

  • Vascularized: containing blood vessels or other fluid-bearing vessels or ducts.
  • Composite: made up of various parts or elements.
  • Allograft: a transplanted organ or tissue from one individual to another of the same species with a different genotype. For example, a transplant from one person to another, but not an identical twin, is an allograft.


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Waiting List

A national database maintained by the OPTN of all patients waiting for an organ transplant. It is made up of sublists of patients waiting for specific organs. See Match Run.

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An organ or tissue transplanted into a human from a non-human animal.

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