ASCP BB key terms

The carbohydrate antigen system defined by A and B antigens on red cells and naturally occurring anti-A and anti-B in plasma. It is the most clinically significant system because incompatible transfusion causes immediate intravascular hemolysis.

A protein-based system of more than 50 antigens in which D is the most immunogenic. Anti-D causes severe hemolytic disease of the newborn and delayed hemolytic transfusion reactions.

A variant phenotype with reduced numbers of D antigen sites that may type as negative or weakly positive on immediate-spin testing. Antiglobulin-phase testing is needed, and donor versus patient results are handled differently.

A system whose K antigen is highly immunogenic. Anti-K is a frequent cause of delayed hemolytic transfusion reactions and severe hemolytic disease of the newborn because the antigen is expressed on fetal erythroid precursors.

A system containing Fya and Fyb antigens. The Fy(a-b-) null phenotype is common in people of African ancestry and confers resistance to Plasmodium vivax malaria; anti-Fy antibodies can cause delayed hemolysis.

A system containing Jka and Jkb antigens. Its antibodies are notorious for dropping below detectable levels yet producing a rapid anamnestic response, causing delayed hemolytic transfusion reactions.

A system of antigens adsorbed onto red cells from plasma rather than made by the cells themselves. Antibodies are usually IgM, react best at room temperature, and are seldom clinically significant.

A system including M, N, S, s, and variant antigens. Anti-S and anti-s can cause hemolytic transfusion reactions and hemolytic disease of the newborn, while anti-M is generally not clinically significant.

The tendency of an antibody to react more strongly with red cells homozygous for its antigen than with heterozygous cells. It is classically seen with Rh, Kidd, Duffy, and MNS antibodies.

A method that detects IgG antibody in serum by incubating serum with reagent red cells, washing away unbound protein, then adding antihuman globulin to reveal sensitization as agglutination.

A test that detects in vivo coating of a patient's red cells with IgG or complement by adding antihuman globulin to washed cells. It is used to investigate immune hemolysis and transfusion reactions.

Testing of patient serum against two or three group O reagent cells with known antigen profiles to detect unexpected antibodies before transfusion. A negative screen with valid records permits electronic crossmatching.

A set of reagent red cells with known antigen phenotypes used to determine the specificity of an antibody detected in the screen, usually by pattern analysis and selected cell testing.

A technique that removes antibody bound to red cells so the recovered antibody can be tested for specificity. It is used in investigating hemolytic disease of the newborn and delayed reactions.

Removal of antibody from serum by incubating it with red cells bearing the corresponding antigen. Autoadsorption uses the patient's own cells to uncover underlying alloantibodies but is invalid after recent transfusion.

Enhancement media added to antibody detection tests to increase antibody uptake and allow shorter incubation. LISS lowers ionic strength, while polyethylene glycol excludes water and concentrates antibody.

A test method in which red cells migrate through a gel or glass bead column containing antihuman globulin. Agglutinates are trapped in the gel and graded by how far they travel.

A compatibility test performed by centrifuging donor cells and recipient serum without incubation, primarily to detect ABO incompatibility mediated by IgM antibodies before issue of red cells.

Testing of donor red cells against recipient serum to confirm compatibility before transfusion. Immediate-spin and antiglobulin phases detect ABO and other clinically significant incompatibilities.

A computer-based compatibility check used when the antibody screen is negative and historical ABO records agree. It requires validated software, two ABO determinations, and no transfusion history discrepancies.

Pre-transfusion testing consisting of ABO and Rh typing plus an antibody screen. It allows units to be reserved without immediate crossmatching and speeds availability when blood is needed.

A preservative solution such as AS-1, AS-3, or AS-5 added to red cells after plasma removal. It supplies nutrients that extend red cell storage to 42 days.

Removal of white cells from a blood component by filtration to reduce febrile reactions, HLA alloimmunization, and leukocyte-borne cytomegalovirus transmission, typically to fewer than five million residual cells.

Exposure of a component to approximately 25 gray to inactivate T lymphocytes. It prevents transfusion-associated graft-versus-host disease in immunocompromised or related-donor recipients.

The cold-insoluble fraction of plasma, rich in fibrinogen, factor VIII, von Willebrand factor, and factor XIII. It is stored frozen and used mainly for fibrinogen replacement in bleeding patients.

Plasma frozen within hours of collection that retains labile coagulation factors. It is thawed at 30 to 37 degrees Celsius and used to replace coagulation factors in bleeding or before procedures.

Platelets are kept at 20 to 24 degrees Celsius with continuous agitation for up to five days. Bacterial contamination is the leading infectious risk because refrigeration and freezing are not used.

Temporary or permanent exclusion of a prospective donor because of medical history, travel, medications, or abnormal test results, intended to protect recipients from infection and other harm.

Amplification testing of donor samples for HIV, hepatitis C, hepatitis B, and other agents. It is more sensitive than serology and shortens the window period before detectable infection.

The interval after infection during which a donor is infectious but screening tests remain negative because markers have not yet reached detectable levels.

The process of identifying and notifying recipients of prior donations from a donor later found positive for a transfusion-transmitted infection, and quarantining any remaining components.

A temperature rise during or shortly after transfusion caused by cytokines in the component or recipient antibodies against donor leukocytes. It is managed by stopping the transfusion and using leukoreduced products for prevention.

Acute hypoxemia with bilateral pulmonary infiltrates within six hours of transfusion, often caused by donor antibodies against recipient HLA or neutrophil antigens. It is a leading cause of transfusion-related death.

Dyspnea, hypertension, and pulmonary edema from volume overload during or after transfusion. It is managed with diuretics, slower infusion rates, and smaller volumes in at-risk patients.

Rapid destruction of transfused red cells, most often from ABO incompatibility, producing fever, chills, hemoglobinuria, disseminated intravascular coagulation, and acute kidney injury. It requires immediate cessation of the transfusion.

Destruction of transfused red cells three to fourteen days after transfusion by an anamnestic antibody response, with a falling hemoglobin and a positive direct antiglobulin test.

Anti-D antibody given to D-negative mothers to prevent alloimmunization to the D antigen. It is also given after miscarriage, amniocentesis, or significant fetomaternal hemorrhage.

Destruction of fetal red cells by maternal IgG antibodies that cross the placenta, causing anemia, jaundice, hydrops, and kernicterus. It is monitored by titers, antibody testing, and fetal assessment.

An acid elution stain that identifies fetal red cells in maternal blood. The percentage of fetal cells estimates the size of fetomaternal hemorrhage and guides the dose of Rh immune globulin.

Scheduled testing of reagents, equipment, and processes against known standards to verify acceptable performance. Results must be reviewed and acceptable before patient or donor testing is reported.

An external program that sends unknown samples to a laboratory and compares its results with peer laboratories. Participation is required for accreditation and is used to detect systematic testing errors.