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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:

  • a. Newborn up to 28 days old, with a systolic blood pressure less than 60 mm Hg, OR
  • b. 29 days old up to 12 months old, with a systolic blood pressure less than 70 mm Hg, OR
  • c. 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
  • d. 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.

Breakthrough Collaborative term. An aim for spread is an explicit statement summarizing what the organization seeks to achieve in its spread effort. It is the responsibility of executive leaders to ensure that the spread aim is aligned with the strategic goals of the organization.


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.

Board of Directors

The OPTN Board of Directors is the governing body for the OPTN. Directors are elected by the members of the OPTN for two or three-year terms. The general composition of the Board of Directors is set forth in the OPTN Final Rule and includes transplant professionals, HRSA representatives, members of the public, living donors, transplant candidates, recipients, and their families. (Source: OPTN Bylaws, Appendix M)

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).

Business Members

A membership category of the OPTN. A business member is an organization in operation for at least one year that engages in commercial activities with two or more active OPTN transplant hospital, OPO, or histocompatibility laboratory members. (Source: OPTN Bylaws, Appendix M)




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 œeveryone 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.


1) Adherence of patients to medical advice and instructions, especially immunosuppressive drug schedules. 2) 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 dependants, 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.


Data Advisory Committee (DAC)

Dissolved upon effective date of the 2005 OPTN contract, this committee was charged with overseeing all recommendations to the Board of Directors regarding specifications for collecting data on the full continuum of events including pre- and post-transplant events. The DAC also had primary responsibility for recommending to the Board data release policies, data collection procedures, and specific OPTN database elements necessary for data analysis and research functions in support of the OPTN and the Scientific Registry.

Data Working Group (DWG)

Dissolved upon effective date of the 2005 OPTN contract, this group was mutually operated by the OPTN and SRTR contractors, and comprised representatives from both organizations as well as members of the transplant community and government staff. The DWG was charged with in-depth review and consideration of needed revisions (additions and deletions) to the OPTN database in order to comply with contract and regulatory requirements and to further solid organ transplantation research. The recommendations of the DWG were presented to the Data Advisory Committee (DAC) for consideration.

Deaths per Day while Waiting

The calculation of the average number of patient deaths per day while waiting accounts for the candidates removed from the list upon death, as well as former candidates found to have died within 30 days of leaving the list for personal or medical reasons, excluding deaths after a removal for transplant (as described in Wait List Registrations) during the last full calendar year.

Death Rate

The percentage of deaths observed in a group of patients, also referred to as the rate of mortality. In statistics, the death rate is calculated as the number of patient deaths observed per 1,000 patient years. Patient years are calculated based on the actual amount of follow-up time after transplant that recipients are studied.

Deceased Donor

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

Deceased Donor Registration Form (DDR)

The form submitted by the OPO when reporting a new donor to the OPTN. The form contains information on donor demographics, cause of death, procurement and consent, current clinical measures, medical and social history and organ recovery information.

Deceased Donor Transplant

The transplant of an organ from a deceased donor.

Delayed Graft Function (DGF)

A condition in which the transplanted organ does not function properly after the transplant. Many kidneys have a delay before they begin to function adequately. Kidneys can sometimes take as long as 3 to 4 weeks to achieve adequate function. When this occurs, a kidney recipient needs dialysis until the kidney starts to function.

Department of Health and Human Services (DHHS or HHS)

The department of the federal government responsible for health-related programs and issues.


A disease in which the pancreas does not manufacture an adequate amount of insulin. As a result, the level of sugar in the blood is too high. A leading factor in heart and kidney disease.


A mechanical process designed to partially perform kidney functions, including correcting the balance of fluids and chemicals in the body and removing wastes. See Hemodialysis and Peritoneal Dialysis.

Diastolic Blood Pressure

The bottom number in the blood pressure measurement (80 in a blood presure of 120/80), indicating the pressure in the arteries when the heart is at rest.

Direct Offer

An organ offer that is made by a host OPO directly to another OPO or a transplant center for a specific recipient.

Directed Donation

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

Division of Transplantation (DoT)

DoT is the office within HHS/HRSA whose principal responsibilities include the oversight of management of the Organ Procurement and Transplantation Network (OPTN), the Scientific Registry of Transplant Recipients (SRTR) and the National Marrow Donar Program (NMDP) contracts; public education to increase organ and tissue donation; and technical assistance to organ procurement organizations (OPOs).

Domino Transplant

A procedure in which an organ is removed from one transplant candidate and immediately transplanted into a second patient, with the first patient receiving a new organ from a deceased donor.

Donate Life America

Donate Life America (formerly the Coalition on Donation) was founded by the transplant community in 1992 to educate the public about organ, eye and tissue donation and avoid duplication of effort. Its mission is to drive individuals, organizations and communities to increase the number of designated organ, eye and tissue donors who save and heal lives. DLA’s vision is a nation that embraces organ, eye and tissue donation as a fundamental human responsibility.

Donate Life America assists in mobilizing the transplant community to educate the American public on the need for organ, eye and tissue donation and motivating the public to make an actionable donor designation. Donate Life America publishes brochures, program kits and other materials; provides technical assistance and referral services; coordinates the National Campaign for Organ, Eye and Tissue Donation and identifies measurable best practices. It is comprised of national organizational members and state teams across the United States that coordinate donation related activities at the grassroots level.

Donate Life, Done Vida

Since 2000, Donate Life and its Spanish-translation Done Vida have been the primary slogans and service mark logos of Donate Life America, promoting donation as a forthright, life-affirming action. Donate Life America encourages the widest possible use of its logos and materials in order to provide a sustained, unified national message about donation. Guidelines and policies are in place to ensure consistency, appropriate use, and the integrity of these national logos and materials.

Donation after Circulatory Death (DCD)

Recovery of organs and or tissues from a donor whose heart has irreversibly stopped beating, previously referred to as non-heart-beating or asystolic donation.

Donation Rate

In statistics, the number of actual donors where at least one organ is recovered for the purpose of transplant. One method of computing donation rate is as a percentage of a specified population (e.g., 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, from whom at least onevascularized solid organ is recovered for the purpose of organ transplantation. A living donor is one who donates an organ or segment of an organ for the intent of transplantation.

Donor Histocompatility Form (DH)

The form submitted by the histocompatibility laboratory containing HLA information of a deceased donor when at least one organ is recovered with the intent to transplant, or a living donor's HLA typing and haplotype information for living donors.

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 Pool

A group of people eligible to donate an organ.

Donor Registries

Available 24 hours a day, seven days a week, online registries provide 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 some are affiliated with the local motor vehicle bureau, while others are independently operated or OPO-based.

DonorNet® 2007

A redesign of the original DonorNet application, a component of the UNetsm system. DonorNet focuses on the registration of deceased donors, organ matching, organ offers and placement. The 2007 redesign enables OPOs to input and uniformly display donor data, to make multiple simultaneous electronic organ offers quickly and efficiently and to present donor information in a consistent manner to transplant centers. This new organ offer process focuses priority on quickly registering the organ refusals so the donor coordinator can focus limited time and resources on those transplant centers that have indicated interest in the organ. Effective January 1, 2007.


Early Adopter

Breakthrough Collaborative term. In the improvement process, the opinion leader within the organization who is willing to try new ideas (introduced by innovators) and whose positive results attract others in the organization to adopt the successful changes. [Rogers E. Diffusion of Innovations. 4th ed. New York, N.Y.: The Free Press; 1995].

Early Majority/Late Majority

The individuals in the organization who will adopt a change only after it is tested by an early adopter (early majority) or after the majority of the organization is already using the change (late majority). [Rogers E. Diffusion of Innovations. 4th ed. New York, N.Y.: The Free Press; 1995].

Effective Date of Contract (EDOC)

The date when a contract goes into effect. The EDOC for the current OPTN contract is September 30, 2005.

Effective Request Process

A process developed collaboratively between the hospital and the OPO that culminates in the request to the family using tested and proven methodology.

Electronic Organ Placement Working Group

Established in 2005 by the Operations Committee to guide the development and implementation of the DonorNet® redesign, and to establish direction regarding a number of specific technical, procedural and policy questions and concerns related to electronic notification and organ placement. The group includes representatives from OPOs, Transplant Centers and Histocompatibility Labs, as well as AST, ASTS, AOPO and NATCO.

Eligible Death

For reporting purposes of DSA performance assessments, an eligible death for deceased organ donation is defined as the death of a patient who meets all the following characteristics:

  • Is 75 years old or less

  • Is legally declared dead by neurologic criteria according to state or local law

  • Has body weight of 5 kg or greater

  • Has a body mass index (BMI) of 50 kg/m2 or less

  • Has at least one kidney, liver, heart or lung that is deemed to meet the eligible data definition as defined below:

    • The kidney would initially meet the eligible data definition unless the donor meets any of the following criteria:

      • Greater than 70 years old

      • Age 50-69 years with history of type 1 diabetes for more than 20 years

      • Polycystic kidney disease

      • Glomerulosclerosis greater than or equal to 20% by kidney biopsy

      • Terminal serum creatinine greater than 4.0 mg/dL

      • Chronic renal failure

      • No urine output for 24 hours or longer

    • The liver would initially meet the eligible data definition unless the donor meets any of the following criteria:

      • Cirrhosis

      • Terminal total bilirubin greater than or equal to 4 mg/dL
      • Portal hypertension

      • Macrosteatosis greater than or equal to 50% or fibrosis greater than or equal to stage II

      • Fulminant hepatic failure

      • Terminal AST/ALT greater than 700 U/L

    • The heart would initially meet the eligible data definition unless the donor meets any of the following criteria:

      • Greater than 60 years old

      • 45 years old or older with a history of 10 or more years of HTN or 10 or more years of type 1 diabetes

      • History of coronary artery bypass graft (CABG)

      • History of coronary stent/intervention

      • Current or past medical history of myocardial infarction (MI)

      • Severe vessel diagnosis as supported by cardiac catheterization (that is more than 50 percent occlusion or 2+ vessel disease)

      • Acute myocarditis or endocarditis, or both

      • Heart failure due to cardiomyopathy

      • Internal defibrillator or pacemaker

      • Moderate to severe single valve or 2-valve disease documented by echo or cardiac catheterization, or previous valve repair

      • Serial echo results showing severe global hypokinesis

      • Myxoma

      • Congenital defects (surgically corrected or not)

    • The lung would initially meet the eligible data definition unless the donor meets any of the following criteria:

      • Greater than 65 years old

      • Diagnosed with COPD

      • Terminal PaO2/FiO2 less than 250 mmHg

      • Asthma (with daily prescription)

      • Asthma is the cause of death

      • Pulmonary fibrosis

      • Previous lobectomy

      • Multiple blebs documented on computed axial tomography (CAT) scan

      • Pneumonia as indicated on computed tomography (CT), X-ray, bronchoscopy, or cultures

      • Bilateral severe pulmonary contusions as per CT

If a deceased patient meets the above criteria they would be classified as an eligible death unless the donor meets any of the following criteria:

  • The donor goes to the operating room with intent to recover organs for transplant and all organs are deemed not medically suitable for transplant

  • The donor exhibits any of the following active infections (with a specific diagnosis):

    • Bacterial: tuberculosis, gangrenous bowel or perforated bowel or intra-abdominal sepsis

    • Viral: HIV infection by serologic or molecular detection, rabies, reactive hepatitis B surface antigen, retroviral infections including viral encephalitis or meningitis, active herpes simplex, varicella zoster, or cytomegalovirus viremia or pneumonia, acute epstein barr virus (mononucleosis), West Nile virus infection, or SARS. However, an HIV positive organ procured for transplantation into an HIV positive recipient at a transplant hospital that meets the requirements in Policy 15.7: Open Variance for the Recovery and Transplantation of Organs from HIV Positive Donors would still meet the requirements of an eligible death, according to the OPTN Final Rule.

    • Fungal: active infection with cryptococcus, aspergillus, histoplasma, coccidioides, active candidemia or invasive yeast infection

    • Parasites: active infection with trypanosoma cruzi (Chagas'), Leishmania, strongyloides, or malaria (plasmodium sp.)

    • Prion: Creutzfeldt-Jacob disease

 The following are general exclusions:

  • Aplastic anemia, agranulocytosis

  • Current malignant neoplasms, except non-melanoma skin cancers such as basal cell and squamous cell cancer and primary CNS tumors without evident metastatic disease

  • Previous malignant neoplasms with current evident metastatic disease

  • A history of melanoma

  • Hematologic malignancies: leukemia, Hodgkin's disease, lymphoma, multiple myeloma

  • Active fungal, parasitic, viral, or bacterial meningitis or encephalitis

  • No discernible cause of death


A Chronic Obstructive Pulmonary Disease (COPD) in which an abnormal accumulation of air in tissues or organs, especially of the lungs which results in air trapping within the lungs.

En Bloc (or En-Bloc)

The transplant of both kidneys or both lungs from a single donor into one recipient, where both organs are recovered and transplanted as a single unit.


Serious brain function abnormalities experienced by some patients with advanced liver disease (and other diseases). Symptoms most commonly include confusion, disorientation, insomnia, and may progress to a coma.

End-Stage Liver Disease (ESLD)

Irreversible liver failure that requires transplantation as hepatic replacement therapy.

End-Stage Organ Disease

A disease that leads to the permanent failure of an organ.

End-Stage Renal Disease (ESRD) Program

Part of the Medicare program that provides medical coverage to people with end stage kidney disease or renal failure to help pay for dialysis or transplantation.


The study of incidence, distribution and control of disease in populations.

Epstein-Barr Virus (EBV)

A common virus that remains dormant in most people, but may be a problem in transplant recipients. It has been associated with certain cancers, including Burkitt's lymphoma, immunoblastic lymphoma, and nasopharyngeal carcinoma.


Medical Ethics is the discipline of evaluating the merits, risks, and social concerns of activities in the field 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 is 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) have the right to dignity
  • Truthfulness - patients should not be lied to, and deserves 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. See also Hippocratic Oath, Justice and Utility, Statement of Principles and Objectives of Equitable Organ Allocation.

Ethics Committee

The OPTN standing committee charged with considering ethical issues related to the process of organ procurement, distribution and transplantation. These issues include social impact, the relationship of cost to benefit, impact on patients and their families as well as society at large, legal issues and related public policy, and access to transplantation. The committee will consider the broader implications presented by such issues and will not consider individual patient's issues or disputes.


For OPTN data purposes, the use of categories such as White; Black or African-American; Hispanic; Asian, American Indian/ Alaskan Native; Pacific Islander; Multiracial.

Evaluation Plan

The detailed document describing procedures related to how UNOS as the OPTN contractor assesses OPTN member compliance with OPTN policies and by-laws.

Executive Committee

The standing OPTN Committee composed of no more than 12 Directors: President, Immediate Past President, Vice President, Vice President of Patient and Donor Affairs, Secretary, Treasurer, and if not represented by the individuals holding such offices, at least one of each of the following: an organ procurement organization representative, a transplant coordinator representative, a histocompatibility representative, and a general public, patient or voluntary health organization representative. HRSA's Director of the Division of Transplantation and the OPTN Project Officer or their designees participate ex officio. The UNOS Executive Director attends all meetings of the OPTN Executive Committee but does not vote. The Executive Committee meetings take place immediately prior to both Board of Directors meetings, and may also take place at other times as the need arises. It is authorized to:

  • Act conditionally on behalf of the Board
  • Review time-sensitive issues that require Board action, including the proposal of solutions to conflicts among recommendations of various standing and ad hoc committees
  • Make recommendations to the Board on any issue
  • Provide guidance on the interpretation of prior Board actions, and/or temporarily suspend or modify implementation of recent policy or by-law changes that are not achieving their intended effect
Expanded Criteria Donor (ECD) Kidney

A kidney donated for transplantation from any brain dead donor over the age of 60 years; or from a donor over the age of 50 years with two of the following: a history of hypertension, the most recent serum creatinine greater than or equal to 1.5 mg/dl, or death resulting from a cerebral vascular accident (stroke). This definition applies to the allocation of deceased donor kidneys.

Extra Corporeal Membrane Oxygenation (ECMO)

A system to augment alveolar ventilation by gaseous diffusion of oxygen into blood outside the patient's body.


Outside of, beyond the kidney.


Finance Committee

The OPTN standing committee chaired by the Treasurer. Primarily responsible for the organization's financial operations including approving the annual OPTN budget and recommending the OPTN member registration fee to the OPTN Board of Directors at the beginning of every fiscal year; meeting with the OPTN's compliance auditors annually to review the OMB Circular A-133 audit to ensure that UNOS is compliant with all OPTN contract and Federal regulation requirements; and monitoring OPTN member activity regarding timely payment of OPTN member registration invoices as well as the cash reserve levels of the OPTN.

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.

First Things First

Breakthrough Collaborative term describing priorities addressed by successful teams to assure that change is deep enough into the system to be sustained:

  • Create OPO Hospital Presence/In House Coordinator
  • Analyze and Apply Current Hospital Specific Data
  • Identify Physician/Clinician Champions
  • Conduct Real Time Death Record Reviews
  • Establish Clinical Triggers
  • Hold Donation Team Huddles
  • Identify and Utilize Effective Requesters in Ever Case
  • Conduct After Action Reviews
Food and Drug Administration (FDA)

An agency within the 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.

Forced Expiratory Volume in One Second (FEV1)

A standard measure of lung function which measures the volume of air one breathes out in one second after taking a deep breath. It is also a predictor of mortality in lung patients.

Forced Vital Capacity (FVC)

The maximum volume of gas that can be exhaled after taking a maximum inhalation. A measure of pulmonary function.

Freedom of Information Act (FOIA)

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.


A medical event that occurs very quickly with an acute onset, as in fulminant liver failure. Usually occurs over days and not weeks.

Fulminant Hepatic Failure (FHF)

Acute liver failure with no preexisting liver disease.

Functional Status

A way to measure the effects that lung disease may have on a person’s ability to perform routine daily tasks. Functional status is used in the Lung Allocation Score.

Fungal Disease

Infection that usualy occurs in patients during treatment with steroids or immunosuppressants. Examples of fungi include candidas, aspergillus and histoplasmosis, which tend to affect the whole body and are not localized infections.


Geographic units for organ distribution

Donated organs are first offered to transplant candidates within the Donation Service Area of the host OPO (with the exception of perfectly matched donor kidneys). If the organs are not acceptable for use in the transplant centers in the host OPO's DSA, they are offered transplant centers in the Region, then to all centers nationwide. DSA assignations are determined by CMS.

Glomerular Filtration Rate (GFR)

A measure used to determine kidney function, the GFR indicates the kidney's ability to filter and remove waste products.


A disease or condition resulting in inflammation of the filtering cells of the kidney.


A transplanted organ or tissue.

Graft Survival

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



A set of closely linked genes usually inherited together as a unit, observed to determine genetic compatibility between donor and recipient.

Health Insurance Portability and Accountability Act (HIPAA)

Passed in 1996, HIPAA requires employers to provide health insurance coverage to employees who lose or change jobs, and includes an administrative simplification section which deals with the standardization of healthcare-related information systems including data security, protection of patient confidentiality and privacy. The Act mandates standardized formats for all patient health, administrative, and financial data; unique identifiers (ID numbers) for each healthcare entity, including individuals, employers, health plans and health care providers; and security mechanisms to ensure confidentiality and data integrity for any information that identifies an individual.

Health Maintenance Organization (HMO)

An insurance plan encompassing a network of health care providers including doctors, hospitals, pharmacies, and other medical facilities and professionals where an individual and his/her employer pay a fixed monthly fee for services, regardless of the level of care.

Health Resources and Services Administration (HRSA)

The primary healthcare agency of the federal government that deals with health access issues. Its role is to make essential primary care service available to poor, uninsured and geographically underserved populations. HRSA is a division of the U.S. Department of Health and Human Services (HHS). The Division of Transplantation (DoT) is a component of HRSA's Healthcare Systems Bureau (HSB). HRSA provides funding for the OPTN contract.

Hematocrit (Hct)

The measure of the volume of red blood cells as percentage of the total blood volume. Normal in males is 43 to 49 percent, in females 37 to 43 percent.


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

Hemoglobin (Hgb)

The protein in red blood cells that carries oxygen.


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

Hepatic Encephalopathy

Associated with hepatic failure from any cause, attributed to the passage of toxic nitrogenous substances from the portal to the systemic circulation; cerebral manifestations may include coma.


A viral infection or non-specific inflammation of the liver that can lead to liver failure. Hepatitis C is the leading cause of liver failure that leads to transplantation.

Hepatitis B Virus (HBV)

Formerly called serum hepatitis, it is caused by the hepatitis B virus (HBV). About 10 percent of cases progress to chronic hepatitis. It is spread through intravenous drug use, through sexual contact with infected individuals, through exposure to infected body fluids, and vertically from mother to child. Common symptoms include abdominal pain, fatigue, fever, jaundice, and elevated liver enzymes. A vaccine against HBV is available.

Hepatitis C Virus (HCV)

A form of hepatitis caused by the hepatitis C virus (HCV), previously known as non-A, non-B hepatitis. Most infections are due to injection drug use with contaminated needles. Blood transfusion-associated infections are rarer now than in the past due to improved blood donor screening. The CDC estimates 4.1 million (1.6 percent) Americans have been infected with HCV, of whom 3.2 million are chronically infected. Of the people who have chronic hepatitis C, 10 to 20 percent eventually develop cirrhosis and one to five percent develop hepatocellular carcinoma.


A specialist who is an expert in the diagnosis and treatment of liver diseases.

Heterotopic Transplant

Transplantation of an organ to a site different from where it would ordinarily be located on the recipient's body.

High Blood Pressure (hypertension) (HTN)

When the force of the blood pushing against the walls of the blood vessels is higher than normal because the blood vessels have either become less elastic or have gotten smaller. High blood pressure causes the heart to pump harder to move blood through the body. High blood pressure can cause kidney failure and heart disease if not treated.

High Leverage Changes

Breakthrough Collaborative term. Improvements which have a direct relationship to outcomes/results and are a combination of change package concepts. Example: Six actions to create a high performance, organ donation system:

  1. Advocate Organ Donation As The Mission
  2. Involve Senior Leadership To Get Results
  3. Deploy A Self-Organizing OPO/Hospital Team
  4. Practice Early Referral, Rapid Response
  5. Master Effective Requesting
  6. Implement Donation After Cardiac Death
Hippocratic Oath

A traditional oath of physicians, who pledge to practice medicine according to the ideals and moral principles put forth by Hippocrates: to treat the ill to the best of one's ability, to preserve a patient's privacy, to teach the secrets of medicine to the next generation. Ethics, Justice, Statement of Principles and Objectives of Equitable Organ Allocation, Utility.


The examination of human leukocyte antigens (HLA) in a patient, often referred to as "tissue typing" or "genetic matching." Tissue typing is routinely performed for all donors and recipients in kidney and pancreas transplantation to help match the donor with the most suitable recipients to help decrease the likelihood of rejecting the transplanted organ. See Human Leukocyte Antigen System (HLA System).

Histocompatibility Antigens

Molecules, also known as Human Leukocyte Antigens (HLA), found on all nucleated cells in the body. Inherited from one' parents, histocompatibility antigens help the immune system to recognize whether or not a cell is foreign to the body. These antigens are used to help determine the compatibility of kidneys and pancreata for transplantation from one individual to another. See Human Leukocyte Antigen System (HLA System).

Histocompatibility Committee

The standing OPTN committee charged with considering issues relating to donor and recipient histocompatibility, organ alocation, tissue typing consistency and histocompatibility laboratory qualifications, including cost to benefit ratio and impact on organ transplantation. The committee will consider the broad implications of such issues and will deal with specific individual issues or situations.

HLA Mismatch (MM)

In transplantation, a mismatch indicates the donor has at least one HLA-A, HLA-B, or HLA-DR antigen that is not present in the recipient.

Host OPO

The OPO that identifies a potential donor and assumes responsibility for donor management, procurement and organ allocation.


Breakthrough Collaborative term. A structured multi-disciplinary meeting of hospital and OPO staff used to coordinate the Effective Request Process and to meet the unique needs of each eligible donor's family.

Human Immunodeficiency Virus (HIV)

The virus destroys cells in the immune system, which makes it difficult for the body to fight off infections; toxins, or poisons; and diseases. HIV causes AIDS, a late stage of the virus characterized by serious infections, malignancies and neurologic dysfunctions.

Human Leukocyte Antigen (HLA)

Molecules found on cells in the body that are inherited genetically. In donor-recipient matching, HLAs help to determine compatibility between a donor and recipients.

Human Leukocyte Antigen System (HLA System)

The system for using HLAs help to determine the compatibility of kidneys and pancreata for transplantation from one individual to another. Generally speaking, the smaller the number of HLA mismatches the better the compatibility between donor organ and recipient.


High blood pressure. Occurs when the force of the blood pushing against the walls of the blood vessels is higher than normal because the blood vessels have either become less elastic or have gotten smaller. Hypertension causes the heart to pump harder to move blood through the body. It can cause kidney failure and heart disease if not treated.



Of unknown cause.

Idiopathic cardiomyopathy

Disease of the heart muscle with no known cause leading to a weakened and often enlarged heart; one of the principal reasons for heart transplantation.

Idiopathic pulmonary fibrosis

A chronic progressive interstitial lung disease of unknown cause, characterized by inflammation and fibrosis of the lung parenchyma.

Imminent neurological death

Imminent Neurological Death is defined as the death of a patient who meets both of the following criteria:

  • Meets the eligible death definition with the exception that the patient has not been declared legally dead by neurologic criteria according to current standards of accepted medical practice and state or local law.
  • Has a severe neurological injury requiring ventilator support who, upon clinical evaluation documented in the OPO record or donor hospital chart, has no observed spontaneous breathing and is lacking at least two of the additional brain stem reflexes that follow:

    • Pupillary reaction

    • Response to iced caloric

    • Gag Reflex

    • Cough Reflex

    • Corneal Reflex

    • Doll's eyes reflex

    • Response to painful stimuli

A patient who is unable to be assessed neurologically due to administration of sedation or hypothermia protocol does not meet the definition of an imminent neurological death.

Immune Response

The body's natural defense against foreign objects or organisms, such as bacteria, viruses or transplanted organs or tissue.

Immune System

The organs, tissues, cells and cell products in your body that work to find and neutralize foreign substances including bacteria, viruses and transplanted organs.


A measure of an antigen's ability to provoke an immune response.


Prevention or inhibition of the immune system to respond to foreign substances in the body. Medications often used to prevent a recipient's immune system from rejecting a transplanted organ or tissue include prednisone, methylprednisolone, azathioprine, mycophenolate mofetil, cyclosporine, tacrolimus, and sirolimus, among others.


Relating to the weakening or reducing of your immune system's responses to foreign material; immunosuppressive drugs reduce your immune system's ability to reject a transplanted organ.

Import Match Run

Generated from access to a non-local donor, an import match run is a local record of an OPO's potential recipients for a particular organ (listed in the order which local allocation offers should be made). The potential recipients are sorted according to the relationship between distinct candidate and donor information.

Improvement Leader

Breakthrough Collaborative term. The Improvement Leader organizes and drives the spread project in their donation service area.

Induction Therapy

Medications given for a short finite period in the perioperative period for the purpose of preventing acute rejection. Though the drugs may be continued after discharge for the first 30 days after transplant, it will not be used long-term for immunosuppressive maintenance.


A condition that occurs when a foreign substance, such as bacteria, enters your body, causing your immune system to fight the intruder. All transplant recipients can get infections more easily because their immune systems are suppressed. It is more difficult for them to recover from infection (such as urinary tract infections, colds and the flu).


The swelling, heat and redness produced when the body is injured or infected.

Informed Consent

A person's voluntary agreement, based upon adequate knowledge and understanding of relevant information, to participate in research or to undergo a diagnostic, therapeutic, or preventive procedure.


In the improvement process, the person(s) who goes outside the organization to find new ideas. This person may not be well connected to others in the social system. [Rogers E. Diffusion of Innovations. 4th ed. New York, N.Y.: The Free Press; 1995. Note: Importance of change agents; agenda setting in organizations]


Medications that increase the force of contraction of the heart muscle.

Institutional Review Board (IRB)

A committee of physicians, statisticians, researchers, community advocates, and others that ensures that a clinical trial is ethical and that the rights of study participants are protected.

Intended Candidate

The candidate for whom an organ was accepted.

International Normalized Ratio (INR)

A measure of a patient's coagulation (clotting) system. INR is used in the MELD and PELD calculations.

International Organization for Standardization (ISO)

A non-governmental non-profit organization whose mission is to promote the development of standardization and related activities in the world with a view to facilitating the international exchange of goods and services, and to developing cooperation in the spheres of intellectual, scientific, technological and economic activity.

International Society for Heart and Lung Transplantation (ISHLT)

An international not-for-profit organization dedicated to the advancement of the science and treatment of end-stage heart and lung diseases, comprising more than 2,200 professionals, ISHLT is an OPTN member in the Medical Professional/Scientific Organization category.


A drug or procedure that is not yet Federal Drug Administration (FDA) approved for marketing.

ISO 9001:2008

The quality standards certification obtained by UNOS from the International Organization for Standardization (ISO) to ensure optimal quality of all information technology activities and processes including Organ Center practices, user training and support services, and all processes associated data collection, validation, monitoring and reporting, policy implementation. See International Organization for Standardization.


Joint Commission on Accreditation of Healthcare Organizations (JCAHO)

An independent, nonprofit organization that evaluates and accredits health care 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.


Kidney Allocation Review Subcommittee (KARS)

A subcommittee of the Kidney/Pancreas Allocation Committee, created in 2004 to conduct a comprehensive review of the national system for allocating deceased donor kidneys, including a series of public hearings with expert testimony and open discussion focused on specific aspects of the national kidney allocation system and opportunities for assessment and/or improvement.

Kidney and Pancreas Simulated Allocation Model (KPSAM)

A computer model that simulates the OPTN kidney and kidney-pancreas allocation systems for the assessment of the impact of various kidney policies.

Kidney Transplantation Committee

The standing OPTN committee charged with considering medical, scientific and ethical aspects related to kidney procurement, allocation and sharing. The committee considers both the broad implications and the specific member situations relating to kidney issues and policies.


A pair of organs that remove wastes from the body through the production of urine. All of the blood in the body passes through the kidneys about 20 times every hour. Kidneys can be donated from living and deceased donors and transplanted into patients with kidney failure.


Learning Session

Breakthrough Collaborative term. An intensive two day meeting designed to focus on a set of key components to support effective spread, build learning relationships with other day-to-day spread agents, and support participants in making plans for their organization's spread work.

Left Ventricular Assist Device (LVAD)

A mechanical device implanted into a patient with left heart failure that assists the left ventricle in providing blood circulation.


A law or 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 1985 (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, Uniform Determination of Death Act.


A white blood cell.


For a particular population, the total number of years lived. For example, suppose 10 transplant recipients each lived 30 years following the transplant. As a group, these recipients would have lived 300 life-years.


The largest organ in the body, made up of a spongy mass of wedge-shaped lobes. The liver secretes bile, which aids in digestion, helps process proteins, carbohydrates, and fats, and stores substances like vitamins. It also removes wastes from the blood. A living donor can give part of their liver, after which the liver will regenerate itself in both the donor and recipient.

Liver and Intestinal Organ Transplantation Committee

The standing OPTN committee charged with considering medical, scientific and ethical aspects related or liver/intestine organ procurement, allocation and sharing. The committee will consider broad implications and specific situations among members.

Liver Simulated Allocation Model (LSAM)

A computer model that simulates various OPTN liver allocation system alternatives for the assessment of the impact of various liver policies.

Living Donation

When a living person gives an organ or a portion of an organ for use in a transplant. A kidney, or portion of a liver, lung, pancreas or intestine may be donated. See also Living Donor, Organ Donation.

Living Donor (LD)

A living person who donates an organ for transplantation, such as a kidney or a segment of the lung, liver, pancreas, or intestine. Living donors may be blood relatives, emotionally related individuals, or altruistic strangers. These may also include domino heart or liver transplants. See Domino Transplant.

Living Donor Committee

A permanent standing OPTN committee responsible for considering issues relating to the donation and transplantation of organs from living donors to recipients. The committee makes recommendations to improve the process of living donation and transplantation.

Living Donor Follow-up Form (LDF)

The form submitted by the transplant center at six-months and one year post-donation, containing a living donor's status, clinical measures and complications.

Living Donor Registration Form (LDR)

The form submitted by the transplant center containing living donor demographics, pre-donation clinical measures, surgical information, post-operative information and complications and post-operative clinical measures.

Living-Related Donor (LRD)

A family member who donates a kidney, part of a lung, liver or pancreas to another family member. Examples: a brother and a sister, or a parent and a child.

Living-Unrelated Donor

A person who is not related by blood, who donates a kidney, part of a lung, liver or pancreas to another person (such as a husband, wife, friend or in-law. In the last few years, stranger-to-stranger living unrelated donations have greatly increased).

Local Unit

The geographic area for organ procurement and distribution, usually the OPO's Donation Service Area. See also Alternative Local Units (ALUs), Donation Service Area (DSA), Geographic units for organ distribution.

Lost to Follow-up

A recipient who does not return to the transplant center for medical maintenance after the transplant procedure, or for whom posttransplant information is unavailable.

Lung Allocation Score (LAS)

In the OPTN lung allocation system, every lung transplant candidate age 12 and older receives a lung allocation score, which, combined with blood type, and the geographic distance between the candidates and the hospital where the lung donor is located, is used to determine priority for receiving a lung transplant when a donor lung becomes available. Lungs from pediatric and adolescent donors are offered first to pediatric and adolescent transplant candidates before they are offered to adults. The following medical information is used to calculate a lung allocation score from 0 to 100 for each transplant candidate:

  • Forced Vital Capacity
  • Pulmonary Artery Pressure
  • Oxygen at rest
  • Age
  • Body Mass Index
  • Diabetes
  • NYHA Functional Classification
  • 6-minute walk distance
  • Assisted ventilation
  • Pulmonary Capillary Wedge Pressure
  • Serum Creatinine
  • Disease Diagnosis
Lung Review Board (LRB) )

A national peer review panel established to review estimated clinical values, diagnosis, and exceptional scores submitted by listing centers on behalf of lung transplant candidates.


The organs of respiration in which aeration of the blood takes place, consisting of a right and left lung divided into lobes. The right lung has three lobes and the left lung has two lobes.



A cancer, neoplasm or tumor that grows in an uncontrolled manner, invading nearby tissue and metastasizing (spreading) to other sites through the bloodstream.

Marginal donor

See Expanded Donor.


The compatibility between the donor and the recipient. The more appropriate the match, the greater the chance of a successful transplant.

Match Run

A computerized ranking of transplant candidates based upon donor and candidate medical compatibility and criteria defined in OPTN policies.

Match System

The computerized algorithm used to prioritize patients waiting for organs. It eliminates potential recipients whose size or ABO type is incompatible with that of a donor and then ranks those remaining potential recipients according to the ranking system approved by the OPTN Board.


A partnership between the Federal government and the individual states to share the cost of providing medical coverage for recipients of welfare programs and allowing states to provide the same coverage to low-income workers not eligible for welfare. Programs vary greatly from state to state.


The program of the Federal government that provides hospital and medical insurance, through social security taxes, to people age 65 and over, those who have permanent kidney failure and certain people with disabilities.

Medication Administration Record (MAR)

A history of drug therapy provided to a patient.

Membership and Professional Standards Committee (MPSC)

The standing OPTN committee charged with insuring that OPTN members meet and remain in compliance with OPTN Criteria for Institutional Membership. The MPSC develops, modifies and makes recommendations to the board regarding criteria for institution membership and each class of membership to the Board, reviews membership applications and adopts recommendations to be presented to the Board; monitors members for compliance with membership criteria and policies including transplant center outcomes and activity levels and reviews reported policy violations and makes recommendations to the Board.

Minority Affairs Committee (MAC)

The standing OPTN committee charged with identifying issues which impact organ procurement, allocation and transplantation of minorities. As necessary, the committee conducts research related to specific issues under consideration. The committee provides input and recommendations to the Board of Directors to ensure that issues and needs particular to minority populations are met.

Mismatch (MM)

In kidney transplantation, a mismatch indicates the donor has at least one HLA-A, HLA-B, or HLA-DR antigen that is not present in the recipient.

Model for End-Stage Liver Disease (MELD)

The scoring system used to measure illness severity in liver transplant candidates. This system is used in the allocation of livers to adults, established in February 2002. The MELD system uses three laboratory values (bilirubin, creatinine and INR) to calculate a score that is predictive of the risk of death within three months on the liver waiting list. Livers are allocated to waitlisted patients with chronic liver disease based upon this score. See Pediatric End Stage Liver Disease (PELD) Scoring System.

Model for Improvement

An approach to process improvement, developed by Associates in Process Improvement, which helps teams accelerate the adoption of proven and effective changes. See also Plan-Do-Study-Act.


A disease state or the incidence or frequency of a disease among a population.

Multiple Listing

Being on the waiting list for the same organ at more than one transplant center.


National Kidney Foundation (NKF)

A non-profit national organization whose mission is to prevent kidney and urinary tract diseases, improve the health and well-being of individuals and families affected by these diseases and increase the availability of all organs for transplantation. NKF is an OPTN member in the Voluntary Health Organization category.

National Organ Transplant Act (NOTA)

The National Organ Transplant Act (1984 Public Law 98-507), approved October 19, 1984 and amended in 1988 and 1990, outlawed the sale of human organs and provided for the establishment of the Task Force on Organ Transplantation; authorized the Secretary of HHS to make grants for the planning, establishment, and initial operation of qualified OPOs; and established the formation of the Organ Procurement and Transplantation Network (OPTN) and Scientific Registry of Transplant Recipients (SRTR).


A specialist in the treatment of kidney insufficiency and kidney disease.

New York Heart Association Functional Classification (NYHA)

An assessment of a patient's heart failure based on the severity of symptoms. Range is Class I-IV.


A condition in which a transplanted organ fails to function after being transplanted into a recipient, meaning that the recipient will either have to start dialysis or undergo another transplant. Non-function is rare (less than two percent of all kidney transplants) but is more common in liver transplants.

Non-heartbeating Donor (NHBD)

See Donation after Cardiac Death.


1) Failure of patients to follow the instructions of the medical team, 2) Failure of OPTN members to adhere to the policies and bylaws of the OPTN.

North American Transplant Coordinators Organization (NATCO)

A non-profit membership organization for transplant and procurement clinicians worldwide. NATCO is an OPTN member in the Medical Professional/Scientific Organization category whose president also serves on the OPTN Board of Directors.


Omnibus Budget Reconciliation Act (OBRA)

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. OBRA also established hospital procedures that require a designated person to approach family members about donation at the time of a patient's death. This practice is referred to as Routine Request. In 1987, OBRA was revised to require hospitals to notify OPOs regarding potential donors. See Consolidated Omnibus Budget Reconciliation Act (COBRA).

Operations Committee

The standing OPTN committee formed in July, 2003 to systematically ensure that OPTN policies and systems provide for efficient, effective and measurable organ allocation and distribution, with the aims of a) increasing the utility of donated organs, b) providing for the health and safety of transplant patients while c) instilling public trust in the national transplant system.

OPTN Computer Registration Fee

A fee paid by OPTN members at the time a patient is registered on the organ transplant waiting list or receives a living donor transplant. The fee amount is calculated annually, based upon projected OPTN operating expenses and projected patient registration volume for the year ahead. It is calculated by the OPTN Finance Committee, forwarded to the Board of Directors for approval and given final approval by HRSA.

OPTN Final Rule

The Final Rule (42 CFR Part 121) effective March 16, 2000, further defines the terms and conditions for operation of the OPTN. The Final Rule defines a standard framework for policies, requiring the OPTN to establish Policy Criteria, Policy Objectives and Performance Measures with procedures for continuous evaluation and reporting. Under the terms of the Final Rule, policies intended to be binding upon OPTN members are developed through the OPTN committees and Board of Directors and then submitted to the Secretary of HHS for final approval. The Rule also states that a transplant center must remain a member in good standing. If the member remains non-compliant after due process by the OPTN Membership and Standards Committee, the Board may deem a non-compliant center a Member Not in Good Standing. The case may then be forwarded for review to the Secretary, who could ultimately revoke that center’s eligibility to participate in Medicare.

OPTN Membership

There are five categories of membership to the OPTN:

  • Institutional Members: Organ Procurement Organizations, Transplant Centers and Histocompatibility Laboratories. Required by law. Membership term: indefinite.
  • Medical/ Scientific Members: Professional Scientific or Medical Organizations or Institutions whose membership includes those involved in organ transplantation. Membership term: two years.
  • Public Organization Members: Organizations or institutions engaged in organ donation activities or representing or providing direct support or services to transplant recipients, transplant candidates, or their families; or hospitals that have an interest in the fields of organ donation or transplantation, defined by the referral of at least one potential organ or tissue donor per year for donation. Membership term: two years.
  • Business Members: established organizations or institutions with an interest in the fields of organ donation or transplantation, engaging in commercial activities with two or more active Institutional Members. Membership term: two years.
  • Individual Members: a person with an interest and/or expertise in the fields of organ donation or transplantation. Membership term: two years.

For further details on membership categories and the criteria that must be met to qualify, see Sections 1.1-1.8 of the OPTN Bylaws.


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 Center (OC)

The UNOS Organ Center is responsible for facilitating organ sharing among transplant centers, organ procurement organizations and histocompatibility laboratories across the U.S. The primary functions of the Organ Center are to: assist in placing donated organs for transplantation, assist organ procurement organizations with running the donor/recipient computer matching process, assist with transportation of organs and associated tissues for the purposes of transplantation, act as a resource to the transplant community regarding organ sharing policies. The Organ Center operates 24 hours a day, 365 days a year.

Organ Center Staff

The Organ Center staff consists of 18 full time Organ Placement Specialists, two Organ Center Managers, and a four- person Quality Management Team. The Organ Center day is divided into two 12-hour shifts, and is typically staffed with three Organ Placement Specialists per shift with one Specialist on-call. Additionally, an Organ Center Manager is always available to assist with complex administrative, operational, or policy issues. The Organ Center employs individuals of varied educational backgrounds and employment experiences; however a bachelor's degree is required with a preferred concentration in healthcare or science. Several of the staff have advanced degrees and most have previous clinical experience.

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 Breakthrough Collaborative

The HRSA program launched in 2003 as part of the HHS' Gift of Life Donation Initiative, to 1) identify and promote the best practices in organ donation and procurement for hospitals and OPOs achieving the highest donation rates in the country, and 2) raise the overall donor consent rate to 75 percent among participating hospitals and OPOs. An increase in deceased donors by 4.3 percent occurred from 2002 to 2003 with the donor consents increasing by five percent. The model for the Breakthrough Collaborative was based upon the best-practice strategies developed by HRSA and the Institute for Healthcare Improvement.
The Department of Health and Human Services joined with key national leaders and practitioners from the Nation's transplantation and hospital communities in April 2003 to launch the Organ Donation Breakthrough Collaborative. The Collaborative is intended to dramatically increase access to transplantable organs. The purpose of this initiative is clear, measurable, ambitious, and achievable: Committed to saving or enhancing thousands of lives a year by spreading known best practices to the nation's largest hospitals to achieve organ donation rates of 75 percent or higher in these hospitals.

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

Organ Placement Process

When organs are donated, the host OPO accesses the national transplant computer system through the Internet, or contacts the Organ Center at UNOS. Information about the donor is entered into the system and a donor/recipient match is run for each donated organ. The resulting match list of potential recipients is ranked according to criteria defined in that organ's allocation policy (i.e. blood type, tissue type, size of the organ, medical urgency of the patient as well as time already spent on the waiting list and distance between donor and recipient). Each organ has its own specific criteria.
Using the match list of potential recipients, the host OPO's organ procurement coordinator or the Organ Placement Specialist in the Organ Center contacts the transplant center of the highest ranked patient, based on policy criteria, to be offered the organ. If the organ is turned down, the next potential recipient's transplant center on the match list is contacted until the organ is placed. Once the organ is accepted for a patient, transportation arrangements are made and transplant surgery is scheduled. See also, Wait List, Wait List Registration, Waiting Time.

Organ Placement Specialist

Organ Center personnel responsible for coordinating the organ matching process among OPTN members.

Organ Preservation

Methods used to preserve organs while they are out of the body, between procurement from a donor and transplantation into a recipient.

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 U.S. 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 and 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 the critical need for organ donation. See also Donation Service Area (DSA).

Organ Procurement Organization Committee

The standing OPTN committee charged with considering issues relating to organ procurement organizations and increasing organ procurement efficiency and effectiveness to include medical, scientific and ethical aspects. The committee provides input to other OPTN committees as well as to the OPTN Board of Directors. As necessary, the committee conducts research related to specific issues under consideration.

Organ Transplant Breakthrough Collaborative (OTBC)

An extension of the ODBC, the focus is to increase organ utilization. Specifically, the aim of this collaborative is to increase the mean number of recipients transplanted per donor from 3.06 (2004 U.S. mean) to 3.75 or higher. Success in this initiative is wholly dependent on the active participation of three estates: Transplant Programs, Donor Hospitals, and Organ Procurement Organizations.



Irregularly shaped gland that lies behind the stomach and secretes pancreatic enzymes into the small intestines to aid in the digestion of proteins, carbohydrates and fats. Islet cells within the pancreas secrete glucagon, which regulates blood sugar levels and insulin, which lowers blood sugar levels. If the pancreas fails, the individual becomes diabetic, and may need to take insulin. The pancreas can be donated and transplanted.

Pancreas Transplant Alone (PTA)

A type of isolated pancreas transplantation.

Pancreas Transplantation Committee

The standing OPTN committee charged with considering medical, scientific and ethical aspects related to pancreas procurement, allocation and sharing. The committee considers both the broad implications and the specific member situations relating to pancreas issues and policies.

Panel Reactive Antibody (PRA)

The percent PRA value is a measure of a patient's level of sensitization to HLA antigens. It is the percentage of cells from a panel of blood donors against which a potential recipient's serum reacts. The PRA reflects the percentage of the general population that a potential recipient makes antibodies (is sensitized) against. For example, a patient with a PRA of 80 percent will be incompatible with 80 percent of potential donors. Kidney patients with a high PRA are given priority on the waiting list. The higher the PRA, the more sensitized a patient is to the general donor pool, and thus the more difficult it is to find a suitable donor. A patient may become sensitized as a result of pregnancy, a blood transfusion, or a previous transplant.

Past Medical History (PMH)

A record of a patient or donor's past medical problems.

Past Surgical History (PSH)

A record of a patient or donor's past surgeries.

Patient Affairs Committee

The standing OPTN committee charged with advising the Board of Directors and other committees about patient and donor family perspectives on proposed policies and issues and acting as an advocate for organ donors and transplant candidates and recipients.

Patient Self-Determination Act (PSDA)

In effect since 1991, the Act gives adults with the capacity to make their own medical decisions the right to make decisions today about health care treatment they would want to receive in the future if they could not communicate what they want at that time. The law requires that hospitals, nursing homes and other health agencies give all patients information about their right to have a legal document called an Advance Directive. See Advance Directive for Healthcare.

Patient Survival

The length of time a patient survives after receiving a transplant.


This term is synonymous with life-years and refers to the total number of years lived by a group of people. It is sometimes used in rate calculations. For example, if 100 candidates each spent one year waiting for a transplant during a specified period and 50 were transplanted, the transplant rate for this group would be 50 transplants per 100 patient-years on the waiting list.


A blood gas test is performed to measure the amount of C02 in the blood. When the lung’s ability to exchange oxygen and C02 becomes impaired, the PC02 level may become increased. The candidate’s current PC02 and change in PC02 are both considered in the lung allocation score calculation to reflect worsening PC02 values. PCO2 is used in the Lung Allocation Score.

Pediatric End Stage Liver Disease (PELD) Scoring System

A measure of illness severity used in the allocation of livers to pediatric candidates, established in February 2002. The PELD system uses three laboratory values (albumin, bilirubin and INR), a presence of growth failure (at least 2 standard deviations below average height or weight), and an indicator of whether the patient is less than one year of age to calculate a score predictive of the risk of death within three months on the liver waiting list for candidates under the age of 18. See Model for End-Stage Liver Disease (MELD).

Pediatric Transplantation Committee

The standing OPTN committee charged with considering medical, scientific and ethical issues relating to organ procurement, allocation and sharing for pediatric patients. These issues include: pre- and postoperative care, expeditious transplantation of children, and the specific medical, social and psychological needs of children. The committee considers the broad implications of such issues and will deal with these specific issues or situations as needed.

Peer Review

Evaluation of a professional's activity or performance by other professionals in the same field. Peer review plays an important role in OPTN activities. The Membership and Professional Standards Committee (MPSC) helps to ensure adherence to policies and membership criteria, consistent application of OPTN standards of practice, and equitable treatment of patients in the transplant community.


In statistical analysis, the Nth percentile measure is the value at which N% of the cases are at or below that percentile. For instance, for liver waiting list registrations in 1998, the 25th percentile for waiting time is 140 days. This means that by 140 days after being added to the liver-transplant waiting list, 25 percent of registrants had been transplanted. For the same group, the median for waiting time was 390 days. The median is defined as the 50th percentile. For this group of liver registrants, 50 percent had been transplanted by 390 days.


The passage of a fluid (blood or other) through the vessels of organs or tissues. Deceased organs are perfused with synthetic cold preservation fluid to keep them viable for transplant.

Peripheral Vascular Disease (PVD)

A condition in which the arteries that carry blood to the arms or legs become narrowed or clogged. This interferes with the normal flow of blood, sometimes causing pain, but often causing no symptoms at all. The most common cause of PVD is atherosclerosis (often called "hardening of the arteries"). In some cases, PVD may be caused by blood clots that lodge in the arteries and restrict blood flow.

Peritoneal dialysis

A treatment technique for kidney failure that uses the patient's own body tissues inside of the (abdominal cavity to act as a filter. The intestines lie in the abdominal cavity, the space between the abdominal wall and the spine. A plastic tube called a "dialysis catheter" is placed through the abdominal wall into the abdominal cavity. A special fluid is then flushed into the abdominal cavity and washes around the intestines. The lining (peritoneum) of the abdominal cavity and of intra-abdominal organs act as a filter between this fluid and the blood stream. By using different types of solutions, waste products and excess water can be removed from the body through this process.


The process of alocating donated organs via the match system.

Plan-Do-Study-Act (PDSA)

The four steps used in the Model for Improvement developed to enhance organization performance; a cycle of developing, testing, measuring and implementing changes that result in improvement: The steps are as follows:

  • PLAN - State objective (what needs to be improved) and identify metric for measuring accomplishment of the objective; make predictions, hypotheses and develop a plan to carry out cycle
  • DO - Carry out the test, collect data or other info/ input needed; document problems, unexpected observations; and begin analysis of data
  • STUDY - Complete analysis of data; compare data to predictions; and summarize what was learned
  • ACT - Determine what changes are to be made, identify remaining and new questions and repeat the PDSA to continue exploring and implementing changes that result in progress toward stated objectives

The PDSA cycle was proven effective by the Organ Donation Breakthrough Collaborative and is being implemented throughout OPTN programs and polices. It is based on The Improvement Guide: A Practical Approach to Enhancing Organizational Performance, by Gerald J. Langley, Kevin M. Nolan, Thomas W. Nolan, Clifford L. Norman and Lloyd P. Provist. Published by Jossey-Bass. See also Model for Improvement.


A process in which plasma is removed from blood and the remaining components, mostly red blood cells, are returned to the donor. The process may be used in transplantation to remove pre-formed antibodies.

Policy Development Process

The continuous process by which the OPTN creates, refines and implements ethical, evidence- and consensus-based policies and standards for the procurement, allocation, distribution and transplantation of organs in the U.S.

Policy Oversight Committee

Established by the 2005 OPTN contract, this committee is charged with review policies (existing and proposed) to assess whether they are helping to meet the goals and metrics set forth by the OPTN Strategic Plan and HRSA's program goals. The POC is responsible for:

  • Supporting and improving the efficiency of the OPTN policy development and process for deliberation
  • Ensuring that allocation policies meet certain performance improvement standards
  • Supporting ongoing operation and improvement of data collection systems
  • Reviewing proposed research projects to ensure continued understanding of organ donation and transplantation issues that will ultimately improve the performance of the national transplantation system
Polycystic Kidney Disease (PKD)

A hereditary condition that results in the formation of cysts throughout the kidneys. Patients with PKD often require kidney transplantation.

Posttransplant lymphoproliferative disorder (PTLD)

A spectrum of lymphoid tissue disease ranging from benign infections (mononucleosis) to highly malignant lymphomas.

Posttransplant Malignancy Form (MAL)

The form submitted by the transplant center when a posttransplant malignancy is reported on the transplant recipient follow-up record. The MAL form includes information about the type of malignancy, diagnosis, treatment and outcome.

Potential Donor

A patient who meets the criteria for brain death with no absolute contraindications to organ donation as defined by a standardized list from the International Classification of Diseases, Ninth Revision.

Potential Transplant Recipient (PTR)

A transplant candidate who has been ranked by the computer matching system as the person to whom an organ from a specific deceased organ donor is to be offered.

Preferred Provider Organization (PPO)

A health insurance plan with an established network of healthcare providers. It provides maximum benefit coverage when services are obtained from provider within the network. Reduced benefits generally apply for using health care providers outside of the network.

Premature Ventricular Contractions (PVCs)

Early or extra heartbeats that commonly occur and are usually harmless in normal hearts, but can cause problems in hearts with pre-existing disease.


Method used to keep organs viable between procurement and transplantation. The length of time organs and tissues can be kept outside the body vary depending on the organ, the type of preservation fluid, and the preservation method (pump or cold storage).

Prework Packet

Breakthrough Collaborative term. A document containing a complete description of the Initiative, along with expectations and activities to complete prior to the first Learning Session of the Initiative.

Prework Period

Breakthrough Collaborative term. The time prior to the first Learning Session when teams prepare for their work in the Spread Initiative, including designating both a senior leader and a day-to-day spread agent, establishing a team, developing preliminary aims and measures and summarizing work in progress in a storyboard.

Primary Non-Function

A condition in which a transplanted organ fails to function soon after being transplanted into a recipient, meaning that the recipient will either have to start dialysis or undergo another transplant. Primary non-function is rare (less than two percent of all kidney transplants) but is more common in liver transplants.


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

Program Goals

A set of annual and 10-year performance goals for the national transplant network established by the Department of Health and Human Services within the Federal Government. They include measurable objectives relating to increasing the number of donors and transplants, increasing life years gained among kidney recipients and increasing operational efficiency of the OPTN. The OPTN contract requires the OPTN to play a significant and substantive role in achieving these goals.

Public Comment

A pivotal step in the policy making process, public comment assures that the perspectives and concerns of the general public are taken into account and addressed in policy proposals. Generally speaking, the period for public comment is 45 days. The sponsoring committee creates a public comment document that contains the rationale, the proposal itself and summaries of both. After the document is approved by the Executive Committee, it is distributed to all OPTN members and interested public. The document is mailed to those who request a paper copy, and an email notification containing a link to the document on the OPTN Web site is sent to the others. Public comment materials are also distributed at regional meetings.

The sponsoring committee considers the comments, provides additional information as needed, modifies the proposal as it deems appropriate, or dismisses the proposal for further consideration. Final recommendations are developed for the Board of Directors. The Board reviews the summary of public comments and the final recommendation by the committee, and votes to accept, reject, or modify and accept the proposed policy with a future implementation date.


Breakthrough Collaborative term. A strategy in the OTBC Change Package where transplant programs work to optimize organ acceptance and success rates for each organ type. The purposes of the Pull Strategy are to:

  • Evolve an effective game plan for accepting all organs
  • Understand and guide the capacity to transplant more organs in the DSA
  • Maximize the likelihood of patients having a successful transplant rather than dying on the waiting list
  • Assure transplant program practice is as aggressive as possible
  • Create relationships with OPOs in other DSAs to assure the capacity to receive organs is fully utilized

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

Pulmonary Function Tests (PFTs)

Diagnostic tests that help to measure the lungs' ability to exchange oxygen and carbon dioxide appropriately.


A medical specialist who is an expert in the diagnosis and treatment of lung diseases.


An apparatus for forcing a gas or liquid from or to any part. In organ preservation, pump is a reference to the mechanical perfusion pump that is used to continuously perfuse a recovered organ with a chilled preservation solution.

Pump Time

The number of hours between the time the organ is connected to the preservation pump and cold preservation fluid circulates through the organ, and the time the organ is removed from the pump.


Breakthrough Collaborative term. A strategy in the OTBC Change Package where organs are placed aggressively and strategically. The purposes of the Push Strategy are to:

  • Conduct an exhaustive and relentless search to identify a compatible recipient for every transplantable organ
  • Organize to use exports and imports to assure high acceptance and transplantation rates
  • Staff and standardize an increasingly effective placement process
  • Use information and feedback to build trust and confidence in organ quality, information quality, and efficient matching

Inflammation and/or infection of the kidney and the renal pelvis (part of the system that conveys urine from the kidney to the bladder).



See Ethnicity.


A person who receives a transplant.

Recipient Histocompatibility Form (RH)

The form submitted by the histocompatibility laboratory when a patient is removed from the waiting list as transplanted or when living donor feedback is completed for patients who are not listed. The RH contains information on recipient HLA, panel reactive antibody, crossmatch and donor HLA.

Recovery (Organ)

The surgical procedure of removing an organ from a donor.

Referred Death

Refers to all deaths or imminent deaths reported by a hospital to the OPO within the Donation Service Area (DSA).

Refusal Reasons

Number codes used on a match run to show the reason an organ was not accepted for a potential transplant recipient (PTR) receiving the offer.

Regional Administrator (RA)

UNOS staff person who serves as a resource regarding OPTN information, policies and procedures to members in designated Regions. RAs assist Regional Councillors with planning and conducting regional meetings (and drafting agendas, minutes and correspondence), coordinating regional communications and ensuring regional activities and issues are documented and addressed appropriately. RAs are available to answer questions regarding regional representation, and routinely provide information and materials on the following topics:

  • Responsibilities of Regional Councillors and Associate Councillors
  • Responsibilities of Regional Administrators
  • Directory of regional members by category and state
  • Roster of regional representatives to national committees
  • Regional guidelines (if applicable)
  • Member voting status sheet
  • Previous regional meeting minutes and regional issues
  • Previous Board of Directors' actions affecting regions

See also Region, Regional Associate Councillor, Regional Councillor.

Regional Associate Councillor

Regions elect an Associate Councillor who wil eventualy succeed the Regional Councilor. Each region determines the guidelines for the election procedures. Councillors and Associate Councillors serve one to two years and cannot succeed themselves in office. 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. The Associate Councillor may attend the Board of Directors meeting in the Regional Councillor's absence to participate in discussions and represent the regional views. However, Associate Councillors may not vote on behalf of Councillors. See also Region, Regional Administrator, Regional Councillor.

Regional Councillor

Each Region elects a Regional Councillor to represent regional views and opinions to the Board of Directors. Each region determines the guidelines for the election procedures. Councillors and Associate Councillors serve one to two years and cannot succeed themselves in office. Once elected as a Regional Councillor, that person's name is added to the ballot for election to the Board of Directors. Since all members of the Board of Directors must be elected by a vote of a quorum of the entire membership, Regional Councillors are included on the ballot and elected to the board in the same manner as the other candidates. The Regional Councillor provides leadership to the Region, facilitating information sharing, mediating differences, conducting regional meetings at least twice yearly, nominating regional representatives to OPTN committees, upholding policies and by-laws and communicating information affecting transplant practices and policies to the regional membership. See also Region,

Regional Review Boards (RRBs)

Peer review panels established in each of the 11 Regions to review all urgent status listings for liver and heart candidates. The RRB reviews justification forms submitted by each center documenting the severity of the candidate's illness and justifies the status at which the candidate is listed. Liver RRBs review listings for all liver candidates in Status 1, special case exceptions for MELD/PELD liver candidates, and hepatocellular carcinoma (HCC) candidates. Thoracic RRBs review listings for heart candidates in Status 1A and special case heart candidates in Status 1B. These boards also consider appeals of cases initially turned down for a particular medical urgency status. In 2004 a national Lung Review Board was established. See also Conflict of Interest, Lung Review Board (LRB), Peer Review.


For the administration of organ allocation and appropriate geographic representation within the OPTN policy structure, the membership is divided into 11 geographic regions. Members belong to the Region in which they are located. The Regions are as follows:

  • Region 1 - Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island
  • Region 2 - Delaware, District of Columbia, Maryland, New Jersey, Pennsylvania, Northern Virginia, West Virginia
  • Region 3 - Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, Puerto Rico
  • Region 4 - Oklahoma, Texas
  • Region 5 - Arizona, California, Nevada, New Mexico, Utah
  • Region 6 - Alaska, Hawaii, Idaho, Montana, Oregon, Washington
  • Region 7 - Illinois, Minnesota, North Dakota, South Dakota, Wisconsin
  • Region 8 - Colorado, Iowa, Kansas, Missouri, Nebraska, Wyoming
  • Region 9 - New York, Vermont
  • Region 10 - Indiana, Michigan, Ohio
  • Region 11 - Kentucky, North Carolina, South Carolina, Tennessee, Virginia

A phenomenon that occurs when a recipient's immune system attacks a transplanted organ, tissue, or cell. Immunosuppressive drugs help prevent or treat rejection.


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

Required Request

Hospitals must tell the families of suitable donors that their loved one's organs and tissues can 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.


Due to rejection or failure of a transplanted organ, some patients receive another transplant.


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

Right Ventricular Assist Device (RVAD)

A mechanism implanted into a patient with heart failure that maintains right ventricular blood circulation which is circulation from the heart through the lungs.

Risk Pools

State-created, nonprofit associations that do not require tax dollars for operational purposes. The risk pools are a temporary stopping place for individuals who are denied health insurance for medical reasons. Risk pools often help individuals who, because of their physical condition, are unable to purchase health insurance at any price.

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.


Scientific Registry of Transplant Recipients (SRTR)

As called for by the National Organ Transplant Act (NOTA), the purpose of the SRTR is to provide ongoing evaluation of clinical data about donors, transplant candidates, and recipients, as well as patient and graft survival rates. With oversight and funding from the DoT, the SRTR is currently administered by the Chronic Disease Research Group (CDRG) of the Minneapolis Medical Research Foundation (MMRF).


Transplant candidates are "sensitized" if their immune system makes antibodies against a general donor pool. Sensitization usually occurs as a consequence of pregnancy, blood transfusions, or previous transplantation. The degree of sensitization is measured by panel reactive antibody (PRA). Highly sensitized patients are less likely to match with available donors and more likely to reject an organ than unsensitized patients.

Sharing Agreement, Sharing Arrangement

The OPTN Board-approved arrangement entered into by two or more OPOs to share organs. With the exception of arrangements that are approved for a finite time period to test a hypothesis, OPOs participating in sharing agreements must have geographically contiguous service areas.

Site Survey

Field reviews of OPTN members conducted by OPTN staff to determine compliance with OPTN Policies. The site survey results are reviewed during the peer review process of the OPTN Membership and Professional Standards Committee.

Social Security Act, Section 1138

Federal legislation requiring all U.S. 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.

Split liver

A split liver transplant occurs when the donor liver is divided into segments and then transplanted. These segments may be transplanted into more than one recipient, or a segment could be transplanted into a child for whom an entire adult liver would be too large.

Spread Strategy

Breakthrough Collaborative term. The process by which an innovation is communicated through certain channels over time among members of a social system, as defined by Everett Rogers (1995).

Standard Criteria Donor (SCD)

A donor who does not meet the criteria for DCD or ECD.

Standard Criteria Donor (SCD) Kidney

A kidney donated for transplantation by a donor who has suffered brain death (i.e., is not a donor after cardiac death) and who is not an expanded criteria kidney donor. See Donor After Cardiac Death and Expanded Criteria Donor Kidney.

Standard Error

The standard error measures the level of precision associated with an estimate for a population, usually the mean. Categories that include a large number of transplants generally have small standard errors, while categories with relatively few transplants generally have large standard errors. Survival rates associated with a smaller standard error are more precise than those associated with a larger standard error. Standard errors are presented in the graft and patient survival rates tables.

Statement of Principles and Objectives of Equitable Organ Allocation

Ethical guidelines for creating equitable policies, drafted and circulated to more than 12,000 individuals for public comment, discussed at two public forums, revised accordingly and passed by the Board in June, 1994. The Statement of Principles and Objectives of Equitable Organ Allocation calls policymakers to seek balance among four tenets:

  • Enhance availability of transplantable organs
  • Allocate organs based upon medical criteria, striving to give equal consideration to medical utility (i.e., net medical benefit to all transplant patients as a group) and justice (i.e., equity in the distribution of the benefits and burdens among all transplant patients)
  • Provide transplant candidates reasonable opportunities to be considered for organ offers within comparable time periods, taking into consideration similarities and dissimilarities in medical circumstances as well as technical and logistical factors in organ distribution
  • Respect autonomy of persons

See also Ethics, Hippocratic Oath, Justice, Utility.


An indication of the degree of medical urgency for patients awaiting heart or liver transplants. Examples: status 1A, status 1B, or status 2.

Stem Cells

An embryonic or primitive cell that gives rise to all types of specialized cells.


Naturally occurring hormones in the body that help control important body functions. Synthetic or man-made steroids can be used to suppress the immune system.

Survival Rates

Survival rates indicate the percentage of patients that are alive and the grafts (organs) that are still functioning after a certain amount of time. Survival rates are used in developing OPTN policy.

Systolic Blood Pressure

The top number in the blood pressure (the 120 in a blood pressure of 120/80) measures the maximum pressure exerted on the vessel wall when the heart contracts.


Thoracic Organ Transplantation Committee

The standing OPTN committee charged with considering issues relating to heart and lung procurement, allocation, and transplantation, including medical, scientific and ethical aspects. The committee will consider the broad implications of such issues and will deal with specific individual issues or situations.

Thoracic Organs

Organs located in the chest, i.e., the heart and lungs.

Time to Transplant (TT)

The measure of time from wait-listing to transplantation. Time to transplant considers all candidates who are initially registered on the waiting list, and measures the time between waiting list registration and transplant date. See also Waiting Time (WT).


An organization of a great many similar cells that perform a special function. Examples of tissues that can be transplanted are blood, bones, bone marrow, corneas, heart valves, ligaments, saphenous veins, and tendons.

Tissue Type

An individual's combination of HLA antigens. Matching for tissue type is used in the allocation system for kidney and pancreas transplantation.

Tissue Typing

A blood test that helps evaluate how closely the tissues of the donor match those of the recipient.

Total Artificial Heart

A mechanical pump used to replace the function of a damaged heart, either temporarily or as a permanent prosthesis.

Total Parenteral Nutrition (TPN)

The delivery of nutrients, calories, protein, fat, and/or all caloric needs through a vein into the bloodstream. TPN is used for patients who cannot maintain their nutrition by oral intake.

Transferring Waiting Time

Patients may switch to a different transplant hospital and transfer their waiting time to that hospital. Waiting time from the original center is added to the time collected at the new hospital. See also Waiting Time Modification.

Transplant Administrators Committee

The standing OPTN committee charged with representing the transplant administration community on the Board and striving to optimize transplant services through administrative practices for the benefit of patients and the broader community.

Transplant Candidate Registration Form (TCR)

The form completed and submitted by the transplant center when a patient is added to the waiting list or when living donor feedback is completed for patients who are not listed. The form contains information on candidate demographics, previous transplants, payment, clinical information at time of listing and organ specific medical factors.

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 Coordinators Committee

The standing OPTN committee charged with considering issues that affect the coordination of efforts related to organ procurement, organ allocation, the overall transplant process and the impact of technical innovations on allocation and operations, and how these affect patient/family care, donors and donor families.

Transplant Program

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

Transplant Recipient Follow-up Form (TRF)

The form completed and submitted by the transplant center containing recipient information at six months posttransplant (all but thoracic) and annually thereafter. The form contains patient status, clinical measures at follow-up, graft status, viral detection, treatment and immunosuppression.

Transplant Recipient Registration Form (TRR)

The form completed and submitted by the transplant center when a patient is transplanted. The form contains patient status, pretransplant clinical measures, transplant procedure, post-transplant clinical measures, graft status, treatment and immunosuppression.

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 transplanted, and in some centers, provides follow-up care to the recipient.
  • 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.

Varices (esophageal)

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 posttransplant 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.

Warm Ischemic Time (WIT)

If the donor is a DCD donor, the warm ischemic time is the time from:

  1. The time of Agonal Phase onset to the time when core cooling is initiated.


  1. The calculated time using the serial data to be collected beginning with the agonal phase and ending with the initiation of core cooling.
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.