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The following glossary is excerpted from the Organ Procurement and Transplantation Network with the Department of Health and Human Services. https://optn.transplant.hrsa.gov/resources/glossary/

Allocation Policies

Rules established by the Organ Procurement Transplantation Network (OPTN) to guide and regulate organ allocation and distribution in the United States.


The HLA antigens considered for most matching strategies between a potential recipient and a donor.

ABO Blood Type

The classification of human blood into four groups: A, B, AB, and O.

Action Period

Breakthrough Collaborative term. The period of time between Collaborative Learning Sessions when spread teams work within their organization to meet their spread goals. Participants focus on the spread of ideas and processes within their own organization during this period while staying in continuous contact with other participants and faculty.

Active Candidate

A transplant candidate eligible to be considered for organ offers at a given point in time. Some transplant candidates are temporarily classified as “inactive” by their transplant center because they are medically unsuitable for transplantation or need to complete other eligibility requirements.

Acute Rejection

The host recognizes the graft as foreign and mounts an immunological attack on the graft tissues. Most acute rejections occur in the first year.

Ad Hoc Committees
Ad Hoc Committees are designated in the OPTN Bylaws and are made up of transplant professionals, HRSA representatives, transplant patients, living donors, and members of the public. Unlike the OPTN permanent standing Committees, Ad Hoc Committees do not have representatives designated by each of the OPTN regions. See also Committees. (Source: OPTN Bylaws, Appendix M)
Advisory Committee on Organ Transplantation (ACOT)

Formed by HHS in 2000 and comprising members appointed by the Secretary, the ACOT was established to provide additional input regarding HHS oversight of U.S. organ donation and transplantation activity and policies and their affect on patients.

Agonal Phase

When one of the following conditions is met and sustained for a minimum of five (5) minutes:

  • Newborn up to 28 days old, with a systolic blood pressure less than 60 mm Hg, OR
  • 29 days old up to 12 months old, with a systolic blood pressure less than 70 mm Hg, OR
  • 1 year old up to 10 years old, with a systolic blood pressure less than 70 mm Hg, plus 2 times the age of the patient in years, not to exceed 79 mm Hg, OR
  • 11 years or older, with a systolic blood pressure less than 80 mm Hg, OR when the oxygen saturation is less than 80% at any age.

Albumin is a protein manufactured by the liver. Albumin is used in the PELD calculations as a measure of the severity of liver disease.


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.

Allocation Analysis

Review of the allocation of an organ to determine whether the allocation policies were followed. The analysis is performed by the OPTN contractor through the peer review process of the OPTN Membership and Professional Standards Committee.

Allocation Policies

Rules established by the OPTN to guide and regulate organ allocation and distribution in the United States.


An organ or tissue that is transplanted from one person to another of the same species: i.e. human-to-human. Example: a transplanted kidney.

Alternative Allocation System (AAD System)

Any Board-approved system for local organ allocation or distribution that is different from the standard allocation or distribution system for that organ. Alternative allocation systems are designed to increase organ availability and/or organ quality, reduce or address an inequity in allocation unique to the local area, and/or testing a stated hypothesis intended to benefit the allocation/distribution system overall. There are different kinds of Alternative Allocation Systems: a) Alternative local units (ALUs), b) Sharing arrangements and agreements, c) Alternative point assignment protocols, and d) any combination of the components listed here, See also Alternative local unit (ALU), Sharing arrangements and agreements, Alternative point assignment protocols.

Alternative Local Unit (ALU)

A subdivision of an OPO's Donation Service Area (DSA), approved by the Board to function as a distinct area for organ distribution. See also Alternative Allocation or Distribution System, Regions.

Alternative Point Assignment Protocols

A Board-approved modification to the point system criteria defined in Policies 3.5 through 3.11, applicable to members participating in an approved AAD System. Members participating in an approved alternative point assignment protocol are required to a) stay aware of all provisions in OPTN Bylaws and Policies, b) evaluate the continued benefit of the protocol in light of the policy requirements and overall objectives, and c) obtain Committee and Board approval for any modifications to the protocol.

American Association of Blood Banks (AABB)

An international, not-for-profit association consisting of approximately 1,800 institutions and 8,000 individuals, including physicians, scientists, administrators, medical technologists, nurses, researchers, blood donor recruiters and public relations personnel. Members are located in all 50 states and 80 countries. AABB is an OPTN member in the Medical Professional/ Scientific Organization category.

American Society for Histocompatibility and Immunogenetics (ASHI)

A national not-for-profit association of clinical and research professionals including immunologists, geneticists, molecular biologists, transplant physicians and surgeons, pathologists and technologists. ASHI is an OPTN member in the Medical Professional/ Scientific Organization category whose president serves on the OPTN Board of Directors.

American Society of Multicultural Health and Transplant Professionals (ASMHTP)

A national not-for-profit organization whose mission is to promote organ and tissue donation and transplantation among minorities, and serve in a national advisory capacity for research and education on these and other health related issues. ASMHTP is an OPTN member in the Medical Professional/ Scientific Organization category.

American Society of Transplant Surgeons (ASTS)

A non-profit membership organization of transplant surgeons. ASTS is an OPTN member in the Medical Professional/ Scientific Organization category whose president serves on the OPTN Board of Directors.

American Society of Transplantation (AST)

Founded in 1982, AST is a membership organization of more then 2,200 transplant professionals dedicated to research, education, advocacy and patient care in transplantation. Our goal is to offer a forum for the exchange of knowledge, scientific information and expertise in the field of transplantation. AST is an OPTN member in the Medical Professional/ Scientific Organization category whose president serves on the OPTN Board of Directors.

American Transplant Congress (ATC)

The joint annual meeting of the American Society of Transplantation (AST) and the American Society of Transplant Surgeons (ASTS) designed for physicians, surgeons, scientists, nurses, organ procurement personnel, and pharmacists who are interested in the clinical and research aspects of solid organ and tissue transplantation.


Usually refers to lack of oxygen to the brain.

Anti-Rejection Drugs (immunosuppressive drugs)

Drugs that are used to prevent and/or treat rejection of a transplanted organ.


A protein molecule produced by the immune system in response to a foreign body, such as virus or a transplanted organ. Since antibodies fight the transplanted organ and try to reject it, recipients are required to take anti-rejection (immunosuppressive) drugs.


An antigen is any substance that causes your immune system to produce antibodies against it. An antigen may be a foreign substance from the environment such as chemicals, bacteria, viruses, pollen, or foreign tissues. An antigen may also be formed within the body, as with bacterial toxins.

Antigens determining zero mismatch kidneys (ABDR).

The HLA antigens considered for most matching strategies between a potential recipient and a donor.

Arterial Blood Gases (ABG)

Test used to measure the pH (acidity), oxygen content, and carbon dioxide content of the blood in order to evaluate respiratory diseases and conditions that affect the lungs.


Build-up of fluid in the abdomen, usually associated with liver disease.

Associate Councillor

The associate councillor serves as the regional representative on the OPTN membership and Professional Standards Committee, assists the regional councillor with regional activities, provides leadership to the region in the absence of the regional councillor, and participates in all regional meetings. Each region elects an associate councillor who will eventually succeed the regional councilor. (Source: OPTN Bylaws, Appendix M)
Association of Organ Procurement Organizations (AOPO)

A national nonprofit organization of organ procurement organizations. AOPO is an OPTN member in the Medical Professional/ Scientific Organization category whose president serves on the OPTN Board of Directors.

At-large Committee Member
An at-large member or representative represents the general membership or the public on issues of interest or concern. An at-large member of a committee may also be appointed to provide a certain type of expertise to the committee. (Source: OPTN Bylaws, Appendix M)

A graft of skin or other tissue that is taken from the body of the person to be grafted rather than from another person.

Auxiliary Transplant

A type of liver transplant in which the patient's liver remains within the body, while another whole or partial liver is transplanted just beneath or adjacent to the recipient's.


A measurement or standard that serves as a point of reference by which performance of a process is measured.


Not malignant.

Best Practices

Processes and activities that have been shown in practice to be the most effective.

Biliary atresia

The congenital closure, or near closure, of the bile ducts. The most common indication for liver transplantation in children comprising 60 to 70 percent of all candidates.


A breakdown product of hemoglobin from blood cells, the results of which are used in the MELD and PELD calculations as a measure of the severity of liver disease.


A tissue sample from the body, removed and examined under a microscope to diagnose for disease, determine organ rejection, or assess donated organs or tissues.

Blood Type

One of four groups (A, B, AB or O) into which blood is classified. Blood types are based on differences in molecules (proteins and carbohydrates) on the surface of red blood cells.

Blood Vessels

The veins, arteries and capillaries through which blood flows in the body. Certain blood vessels can be donated and transplanted.

Body Mass Index (BMI)

A measure of body size, calculated as weight in kilograms divided by height in meters squared.

Brain Death

Irreversible cessation of cerebral and brain stem function; characterized by absence of electrical activity in the brain, blood flow to the brain, and brain function as determined by clinical assessment of responses. A brain dead person is dead, although his or her cardiopulmonary functioning may be artificially maintained for some time.

Breakthrough Collaborative

See Organ Donation Breakthrough Collaborative (ODBC), Organ Transplant Breakthrough Collaborative (OTBC).

Cadaveric Transplant

The transplant of an organ from a deceased donor. The preferred term is Deceased Donor Transplant.




A person registered on the organ transplant waiting list. When an organ is offered on behalf of the candidate, he or she is then referred to as a Potential Transplant Recipient (PTR).


Having to do with, or referring to, the heart.

Cardiac death

Death defined as the irreversible cessation of circulatory and respiratory functions. Death is declared in accordance with hospital policy and applicable state and local statues or regulation.

Cardiac Output (CO)

The volume of blood pumped out of the heart per minute.


A specialist who is an expert in the diseases of the heart and associated blood vessels.


A weakening of the heart muscle or change in heart muscle structure that causes varying degrees of reduced heart function.


Typically, a statistical term used in survival analysis to indicate an observation in which the outcome of interest has not yet occurred. For example, in a graft survival analysis, a transplant with a functioning graft may be censored at the last follow-up date because the graft is still functioning. Mathematically, censored observations are included in the analysis up to the point in time at which they are censored.

Center of Excellence

An insurance term for a medical center that will negotiate a discounted price even if that center is not part of the insurance's company's preferred provider network (PPO).

Centers for Medicare & Medicaid Services (CMS)

Formerly titled the Health Care Financing Administration, CMS is an agency of the U.S. Department of Health and Human Services (HHS) responsible for administering the Medicare and Medicaid programs, which provide health care coverage to America's aged, disabled and indigent populations.

Central Venous Pressure (CVP)

The venous pressure as measured at the right atrium of the heart, obtained by means of a central venous catheter whose distal end is attached to a manometer.

Cerebrovascular accident (CVA)

Also known as a stroke, occurring when there is an occlusion of an arterial vessel going to the brain, or when there is bleeding into the brain.

Change Concept

Breakthrough Collaborative term. A general idea for changing a process. Change concepts are usually at a high level of abstraction, but evoke multiple ideas for specific processes. Establish strong culture of accountability for results, use data-driven decision making to determine priorities, and create and maintain visual presence of OPO staff in donor hospitals, are examples of change concepts.

Chief Complaint

The primary symptom that brought the patient to the physician.

Child-Turcotte-Pugh (CTP) Score

A measurement of liver dysfunction that was used in OPTN liver allocation policy between January 19, 1998, and February 26, 2002. The MELD score has replaced it for allocation purposes, but CTP is still used by some to assess function, and remains a measure for minimum listing eligibility.


When one organism possesses cells with more than one genetic background, as in transplant recipients.


Developing slowly and lasting for a long time, possibly the rest of a person's life. For example: chronic kidney failure.

Chronic Disease Research Group (CDRG)

A division of Minnesota Medical Research Foundation (MMRF). MMRF is the nonprofit research subsidiary of Hennepin Faculty Associates, the academic medical group that staffs Hennepin County Medical Center, a teaching hospital in Minneapolis, Minnesota. The CDRG conducts research primarily focused in the areas of chronic kidney disease and organ transplantation. The MMRF-CDRG is responsible for the administration of the Scientific Registry of Transplant Recipients (SRTR).

Chronic obstructive pulmonary disease (COPD)

Chronic obstructive pulmonary disease is a type of lung disease in which the lungs are damaged and results in difficulty breathing. The air passageways in people with COPD have become partly obstructed, impairing airflow in and out of the lungs. The air passageways also become clogged with mucus. A large percentage of COPD cases are caused by cigarette smoking; but there are other causes or contributory factors such as chemicals and other lung irritants.

Chronic Rejection

Slow, continuous immunological attack of the host immune system on the transplanted organ usually resulting in progressive loss of organ function.


A disease of the liver in which normal, healthy tissue is replaced with nonfunctioning fibrous scar tissue and healthy, functioning liver cells are lost; usually occurs when there is a lack of adequate nutrition, an infection or damage caused by alcohol abuse.

Clamp time

The time at which the flow of blood to a particular organ has been clamped off during a procurement.

Clinical Triggers

Criteria for imminent death mutually established by the hospital and OPO which prompt the hospital to make a timely notification to the OPO.

Cockcroft-Gault Formula

A calculation used as a measure of kidney function by estimating creatinine clearance. It is calculated from a patient's serum creatinine, age, weight, and gender. For males: (140-age)*weight/(72*creatinine), where age is measured in years, weight is measured in kilograms and creatinine is measured in mg/dL. The same formula multiplied by 0.85 is used to estimate creatinine clearance for females.


A group of individuals sharing one or more characteristics that are observed during a designated time period.

Cold Ischemia Time (CIT)

The amount of time an organ spends being preserved after recovery from the donor.


A time-limited effort (usually 6 to 12 months) of multiple organizations that come together with faculty to learn about and to create improved processes in a specific topic area. The expectation is that the teams share expertise and data with each other, thus everyone learns, everyone teaches.

College of American Pathologists (CAP)

The principal organization of board-certified pathologists organized to serve and represent the interest of patients, pathologist, and the public by fostering excellence in the practice of pathology and laboratory medicine.

Committee-Sponsored Alternative System

A Board-approved Alternative Allocation/Distribution System developed by one or more OPTN committees that seeks to address concerns particular to multiple local areas but not nationally, or for which consensus to modify the standard policy for the nation as a whole has not been achieved. See also Alternative Allocation or Distribution System.


The OPTN currently maintains approximately 20 standing committees, a fluctuating number of ad hoc committees (established by the President to address a specific issue as it arises), subcommittees and joint subcommittees (created and maintained by standing committees). Committees are comprised of professionals, at least one Patient/ Public representative, Minority Affairs Committee Representative, Pediatric Committee Representative, and one or more SRTR representatives. Permanent Standing Committees also include representatives form each of the 11 Regions. HRSA's OPTN Project Officer and Director of DoT, or their designees, serve as ex-officio non-voting members of all committees. Each committee is provided administrative, policy, analytic, clinical and technical support by one or more committee liaisons from the UNOS staff.


Adherence of patients to medical advice and instructions, especially immunosuppressive drug schedules. Adherence of OPTN members to the policies and bylaws of the OPTN.

Computerized Axial Tomography (CT or CAT Scan)

A series of detailed pictures of areas inside the body created by a computer linked x-ray machine.

Confidence Interval

In statistical analysis, sampling techniques are used to provide an estimate of some aspect of a particular population, for example the average age. This avoids having to take a census of the entire population. Because the estimate is based on a sample and not the entire population, the estimate is subject to error. A confidence interval provides a range of values about the estimate within which the true value (the value of the parameter based on the entire population) lies. The smaller the confidence interval, the more precise the statistical estimate.

Conflict of Interest

A situation in which a board or committee member, employer or institution might benefit from his or her actions as an OPTN volunteer. When a board or committee member has a personal or institutional interest in the outcome of a matter, the member is legally required to disclose the conflict at the beginning of the discussion, and abstain from voting on the matter. Board and committee members are required to sign a conflict of interest agreement when they begin their term of service to the OPTN.


Describes a disease or condition with which someone is born.

Congestive heart failure (CHF)

Any condition that causes the heart to lose its pumping ability to pump blood efficiently. Fluid backs up in the lungs and may also accumulate in the legs.

Consolidated Omnibus Budget Reconciliation Act of 1985 (COBRA)

Federal health coverage protection that requires employers of 20 or more employees to provide employees, and their dependents, the right to continue health insurance benefits when a qualifying event occurs. COBRA lasts for 18 months. OBRA is the federal law that allows an employee to continue health insurance benefits after COBRA, if he/she has elected COBRA coverage due to a Social Security approved disability. OBRA is an 11 month extension of COBRA. See also Omnibus Budget Reconciliation Act (OBRA).

Continuous ambulatory peritoneal dialysis (CAPD)

Continuous dialysis procedure involving a dialysis solution being emptied into the patient's abdominal cavity. This solution removes waste products from the blood, allowing the patient greater freedom of movement.

Conversion, conversion rate

The percentage of times a death meeting eligible criteria (eligible death) becomes an actual donor.

Coronary artery disease

The coronary arteries supply blood (and oxygen) to the heart muscle. When arteries are partially or completely obstructed, the blood and oxygen supply to the heart muscle is impaired. The most common cause of a heart attack.


A synthetic hormone used to reduce the body's normal immune reaction to infection and foreign tissue, such as a transplanted organ. Prednisone is a corticosteroid.


Found in the blood, it is a waste by-product of muscle; creatinine level in the blood is one of the key measures of kidney function.

Criteria (Medical Criteria)

A set of clinical or biologic standards or conditions that must be met.

Critical Pathway for the Organ Donor

A "care map" of an organ donor's treatment plan designed to help critical care staff and procurement coordinators understand, collaborate, and follow the steps required for effective donor management.


A blood test to determine compatibility between donor and recipient. A positive crossmatch indicates incompatibility. If the crossmatch is "negative," then the transplant may proceed. Crossmatching is performed for many organ transplants.

Culture and Sensitivity (C+S)

Culture and Sensitivities tests are done to determine which bacteria cause an infection and the best antibiotic to treat the infection.


A drug used to prevent rejection of the transplanted organ by suppressing the body's defense system. Considered an immunosuppressant.


An encapsulated collection of fluid.

Cystic Fibrosis (CF)

A chronic, progressive, and frequently fatal inherited disease of the body's mucus glands.

Cytomegalovirus (CMV)

A herpes virus that usually causes a mild infection. Important because it can become deadly in an immunocompromised transplant recipient. Deceased donors are screened for the presence of CMV antibodies.

Deceased Donor

An individual, after suffering brain death or cardiac death, from whom at least one solid organ or tissue is recovered for the purpose of transplantation.

Deceased Donor Transplant

The transplant of an organ from a deceased donor.

Directed Donation

The donation of an organ to a specifically identified recipient These instructions are given by a donor or donor family member.

Donation after Cardiac Death (DCD)

Recovery of organs and/or tissues from a donor whose heart has irreversibly stopped beating.

Donation Rate

In statistics, the number of actual donors from which at least one organ is recovered for the purpose of transplantation. One method of computing donation rate is as a percentage of a specified population (eg , eligible deaths divided by donors recovered).

Donation Service Area (DSA)

The geographic area designated by CMS that is served by one organ procurement organization (OPO), one or more transplant centers, and one or more donor hospitals Formerly referred to as Local Service Area or OPO Service Area.


Someone from whom at least one organ or tissue is recovered for the purpose of transplantation. A deceased donor is a patient who has been declared dead using either brain death or cardiac-death criteria. A living donor is one who donates an organ or segment of an organ for the intent of transplantation.

Donor Management

The process and critical pathways used to medically care for donors in order to keep their organs viable until organ recovery can occur.

Donor Registry

Available 24 hours a day, seven days a week, a donor registry provides authorized professionals access to a confidential database of registered organ donors, allowing easy and quick confirmation of an individual’s consent to organ donation. All registries are voluntary and many are affiliated with the local motor vehicle bureau.

Effective Request Process

A process developed collaboratively between the hospital and the organ procurement organization (OPO) that culminates in the request to the family, using tested and proven methodology.


Medical ethics is the discipline of evaluating the merits, risks and social concerns of activities in the eld of medicine Principles include:

  • A practitioner should act in the best interest of the patient (Salus aegroti suprema lex)
  • “First, do no harm” (primum non nocere), from the Hippocratic Oath
  • Autonomy – a patient’s right to choose or refuse treatment (Voluntas aegroti suprema lex)
  • Justice – concerns the distribution of scarce health resources, and the decision of who gets what treatment
  • Dignity – the patient (and the person treating the patient) has the right to dignity
  • Truthfulness – patients should not be lied to and deserve to know the whole truth about their illness and treatment

Principles such as these do not give answers as to how to handle a particular situation, but guide doctors on what principles ought to apply to actual circumstances.

First-Person Consent legislation

Legislation that allows donor designation to be indicated on a driver’s license or an official signed donor document, which gives hospitals legal authority to proceed with organ procurement without consent from the family.

Food and Drug Administration (FDA)

An agency within the U S Department of Health and Human Services responsible for protecting the public health by assuring the safety, efficacy and security of human and veterinary drugs, biological products, medical devices, food supplies, cosmetics and products that emit radiation. The FDA is also responsible for advancing the public health by helping to speed innovations that make medicines and foods more effective, safer and more affordable; and helping the public get the accurate, science-based information they need to use medicines and foods to improve their health. All tissue recovery agencies must be registered with the FDA.

Freedom of Information Act

A federal law giving any person the right to obtain federal agency records, unless the records (or part of the records) are protected from disclosure by any of the nine exemptions contained in the law.

Health Insurance Portability and Accountability Act (HIPAA)

Passed in 996, HIPAA requires employers to provide health insurance coverage to employees who lose or change jobs. The act also involves standardization of healthcare-related information systems including data security, protection of patient confidentiality and privacy.

Health Resources and Services Administration (HRSA)

The primary healthcare agency of the federal government that deals with health access issues HRSA oversees and provides funding for the Organ Procurement and Transplantation Network (OPTN).

Joint Commission on Accreditation of Healthcare Organizations (JCAHO)

An independent, nonprofit organization that evaluates and accredits healthcare organizations and programs in the United States including hospitals, nursing homes and home health agencies. The commission establishes guidelines for the operation of hospitals and other health facilities and conducts survey and accreditation programs.


A law group of laws proposed or enacted that have the force or authority of a state or federal government, or other organization. For transplant-related legislation, see Consolidated Omnibus Budget Reconciliation Act
of 985 (COBRA), OPTN Final Rule, First-Person Consent Legislation, Health Insurance Portability and Accountability Act (HIPAA), National Organ Transplant Act (NOTA), Uniform Anatomical Gift Act, Uniform Brain Death Act and Uniform Determination of Death Act.

National Organ Transplant Act (NOTA)

The National Organ Transplant Act ( 984 Public Law 98-507), approved October 9, 1984, and amended
in 1988 and 1990, outlawed the sale of human organs and provided the establishment of the Task Force on Organ Transplantation; authorized the Secretary of Health and Human Services to make grants for the planning, establishment and initial operation of qualified organ procurement organizations (OPOs); and established the formation of the Organ Procurement and Transplantation Network (OPTN) and Scientific Registry of Transplant Recipients (SRTR).

Non-heartbeating Donor (nHbD)

See Donation after Cardiac Death.


A part of the body made up of tissues and cells that enable it to perform a particular function. Transplantable organs are the heart, liver, lungs, kidneys, pancreas and intestines.

Organ Donation and Recovery Improvement Act

Passed by Congress in 2004, the Organ Donation and Recovery Improvement Act established programs to increase organ donation through public awareness campaigns and education projects, and provided grants programs for individual states supporting use of hospital-based organ procurement coordinators, research and demonstration projects, and reimbursement to living donors for travel-related expenses.

Organ Donation

To give 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 or intestinal organs, and with a live donor, who can give a kidney, or a portion of the liver, lung or intestine.

Organ Procurement

The removal or retrieval of organs from a donor for transplantation.

Organ Procurement and Transplantation Network (OPTN)

In 1987, 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 non-profit, private-sector entity comprised of all US transplant centers, organ procurement organizations and histocompatibility laboratories. These members along with professional and voluntary healthcare organizations and the representatives of the general public are governed by a Board of Directors which reports to the Division of Transplantation, HRSA and, ultimately, HHS UNOS holds the OPTN contract.

Organ Procurement Organization (OPO)

An organization designated by the Centers for Medicare & Medicaid Services (CMS) and responsible for the procurement of organs for transplantation and the promotion of organ donation. OPOs serve as the vital
link between the donor and recipient, and are responsible for the identification of donors, and the retrieval, preservation and transportation of organs for transplantation. They are also involved in data follow-up regarding deceased organ donors. As a resource to the community, OPOs engage in public education on the critical need for organ donation. See also Donation Service Area (DSA).


The surgical procedure of removing an organ from a donor. Also referred to as recovery.


The surgical procedure of removing an organ from a donor.

Required Request

Families of suitable donors who have died in a hospital must be informed that their loved ones’ organs and tissues can be used for transplant. This is usually done by the organ and/or tissue procurement organization with which the hospital has contracted. This law is expected to increase the number of donated organs and tissues for transplantation by giving more people the opportunity to donate.


The surgical procedure of organ recovery. Also referred to as procurement.

Routine Referral

Hospitals are required on or before each death to call the OPO in order to determine suitability for organ, eye and tissue donation. The OPO, in consultation with the patient’s attending physician or his or her designee, will determine the suitability for donation. If the patient is a candidate for anatomical donation, only personnel from the OPO or a designated requestor from the hospital can request donation from the next of kin.

Social Security Act, Section 1138

Federal legislation requiring all US hospitals to establish written protocols for identifying potential organ donors. The Act also requires hospitals to notify their designated OPO of potential organ donors to:

  • Ensure that families of potential organ donors are made aware of the option of organ or tissue donation and their option to decline, and to
  • Encourage discretion and sensitivity by hospitals with respect to the circumstances, views and beliefs of such families

The Act also outlined the responsibilities of OPOs, and required OPOs and hospitals performing transplants to comply with the membership standards and policies of the OPTN.

Transplant Center

A hospital that performs transplants, including qualifying patients for transplant, registering patients on the national waiting list, performing transplant surgery and providing care before and after transplant.

Transplant Program

The organ-specific facility within a transplant center. A transplant center may have programs for the transplantation of heart, lungs, liver, kidneys, pancreata, pancreas islets and/or intestines.

Transplant Team

The diverse group of professionals at the transplant center who work to make a transplant successful. Each person on the Transplant Team is an expert in a different area of transplantation. The Transplant Team includes all or some of the following professionals:

  • Clinical transplant coordinators have responsibility for the patient’s evaluation, treatment and follow-up care
  • Transplant physicians are doctors who manage the patient’s medical care, tests and medications. 
He or she does not perform surgery. The transplant physician works closely with the transplant coordinator to coordinate the patient’s care until
  • Transplant surgeons perform the transplant surgery and may provide the follow-up care for the recipient. The transplant surgeon has special training to perform transplants.
  • Financial coordinators have detailed knowledge of financial matters and hospital billing. The financial coordinator works with other members of the Transplant Team, insurers and administrative personnel to coordinate and clarify the financial aspects of the patient’s care before, during and after the transplant.
  • Social workers help patients and their families understand and cope with a variety of issues associated with a patient’s illness and/or the various side effects of the transplant itself. In some cases, the social worker may perform some of the financial coordinator duties as well
Uniform Anatomical Gift Act (UAGA)

The 1968 Uniform Anatomical Gift Act (UAGA) provided the legal foundation upon which human organs and tissues could be donated for transplantation by execution of an anatomical gift authorizing document. Since 1972, all 50 states and the District of Columbia have adopted this Act, or amended forms of this Act.

Uniform Brain Death Act
Enacted in 1978, the Uniform Brain Death Act expanded the traditional definition of death (cardiopulmonary) to include brain death.

Uniform Determination of Death Act (UDDA)

The 1981 Uniform Determination of Death Act is a model statute defining "brain death." Versions of this Act have been adopted in 39 states and the District of Columbia. The act states that an individual who has sustained either (a) irreversible cessation of circulatory or respiratory functions or (b) irreversible cessation of all functions of the entire brain, including the brain stem, is dead. A determination of death must be made in accordance with accepted medical standards.

United Network for Organ Sharing (UNOS)

The private, nonprofit membership organization that coordinates the nation's transplant system through HRSA's OPTN contract. As OPTN contractor, UNOS is responsible for meeting all contract requirements. As contractor since the first OPTN contract award in 1986, UNOS has established and continually strives to improve tools, systems and quality processes that support OPTN contract objectives and requirements. These include:

  • Managing the national organ transplant waiting list
  • Collecting, managing and reporting of sensitive clinical data in a secure, fail-safe environment
  • Facilitating an open, inclusive forum for development and continuous refinement of evidence-based policies and standards
  • Member and policy performance assessment to ensure equitable, safe treatment of candidates and recipients
  • Increasing donation and making the most of every organ that is donated through professional education, outcomes research, patient services and resources and public and professional education
  • Continuously improving the care, quality of life and outcomes of organ transplant candidates and recipients
United States Renal Data System (USRDS)

The national data system that collects, analyzes, and distributes information about end-stage renal disease (ESRD) in the United States. The USRDS is funded by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) in conjunction with the Centers for Medicare and Medicaid Services (CMS). USRDS collaborates with CMS, the OPTN and the ESRD networks, sharing datasets and actively working to improve the accuracy of ESRD patient information.

Utility and Justice

Because the supply of organs is so limited, policymakers must balance Utility - making the best use of each organ, utilizing every available organ and doing the most good for the most people, with Justice - providing all transplant candidates with equitable access to transplant care and transplantable organs regardless of age, ethnicity, religion, financial status or geography. See also Ethics, Hippocratic Oath, Justice, Statement of Principles and Objectives of Equitable Organ Allocation.


A Board-approved, time-limited experimental OPTN policy designed to test a hypothesis that the change will improve allocation by more effectively addressing fairness, utility, efficiency, need and/or supply. A variance must have a research plan that addresses performance measures, data collection and analysis.


Enlarged and swollen veins at the bottom of the esophagus, near the stomach. A common condition caused by increased venous pressure in the liver. These veins can ulcerate and bleed.


Referring to blood vessels and circulation.


A machine that "breathes" for a patient when the patient is not able to breathe properly.

Ventricular Assist Device (VAD)

A mechanical pump surgically implanted into the heart's atrium or ventricle to aid in pumping blood to the aorta. Most VADs are considered a bridge to transplant for patients with heart failure.

Ventricular Tachycardia (V-tach)

A heartbeat caused by the ventricles that is so rapid the heart does not fill adequately with blood, and less blood is able to pump through the body.


A group of tiny organisms capable of growing and copying themselves while living within cells of the body.

Wait List (WL)

The list of candidates registered to receive organ transplants. When a donor organ becomes available, the matching system generates a new, more specific list of potential recipients based on the criteria defined in that organ's allocation policy (e.g., organ type, geographic local and regional area, genetic compatibility measures, details about the condition of the organ, the candidate's disease severity, time spent waiting, etc.).

Wait List Registration

To be registered for a transplant, a patient undergoes a complete clinical evaluation by the transplant team. If a transplant is needed, the center registers that patient on the Wait List. Within ten days of evaluating a patient for transplant, the transplant center is required to send a letter informing the patient that he or she has or has not been registered on the Wait List. The following registration status categories are used to track waiting patients:

  • Active, describing actively waiting patients whose conditions are favorable for transplant surgery;
  • Inactive, describing patients experiencing conditions (e.g., infection) that temporarily rule out transplant surgery;
  • Removal, describing patients removed from the Wait List a) by personal, voluntary choice, b) because they have become too ill to survive surgery or post transplant immunosuppression, c) are recovering adequate organ function, d) have received a transplant, or e) have died.
Waiting Time

The amount of time a candidate is on the Wait List. Waiting times can be influenced by many factors, including:

  • blood type (some are rarer than others)
  • tissue type
  • height and weight of transplant candidate
  • size of donated organ
  • medical urgency
  • time on the waiting list
  • the distance between the donor's hospital and the potential donor organ
  • how many donors there are in the local area over a period of time and
  • the transplant center's criteria for accepting organ offers

Depending on the kind of organ needed, some factors are more important than others.

White paper

An authoritative report issued by an agency on a particular topic.


An organ or tissue procured from a different species for transplantation into a human.


Transplantation of an animal organ into a human. Although xenotransplantation is highly experimental, many scientists view it as an eventual solution to the shortage of human organs.

Zero Antigen Mismatch (0MM)

This occurs when the donor does not have any HLA-A, B, or DR antigens foreign to the transplant candidate.