Transfusion Medicine & Immunohematology Vocabulary

A comprehensive set of vocabulary flashcards covering key terms, tests, reactions, techniques, and components encountered in transfusion medicine and immunohematology to aid exam preparation.

Antibody Screen

A test using reagent group O screening cells to detect unexpected, clinically significant antibodies in patient serum or plasma.

Alloantibody

An antibody produced against a red-cell antigen that the individual lacks, usually formed after transfusion or pregnancy.

Autoantibody

An antibody that reacts with the individual’s own red-cell antigens, often causing positive DAT results.

HTLA Antibodies

High-titer, low-avidity antibodies that react weakly at AHG phase, are usually clinically insignificant, and often show a characteristic ‘1+ w’ pattern.

Anti-I

A cold-reactive antibody that reacts strongly with adult cells rich in I antigen, weakly with cord cells, and can be neutralized with human milk.

PEG (Polyethylene Glycol)

An enhancement medium that concentrates antibodies and promotes sensitization, increasing the sensitivity of the IAT.

Dosage (in antibody reactions)

The phenomenon in which antibodies react more strongly with cells homozygous for the target antigen than with heterozygous cells.

Neutralization (Antibody ID)

Technique that uses soluble antigen to inhibit a suspected antibody; loss of reactivity confirms antibody specificity.

Rule of Three

Statistical rule requiring ≥3 antigen-positive and ≥3 antigen-negative cells to confirm antibody identification at the 95% confidence level (p = 0.05).

Direct Antiglobulin Test (DAT)

Detects in vivo coating of patient red cells with IgG and/or complement using AHG reagent.

Indirect Antiglobulin Test (IAT)

Detects antibody in serum or plasma reacting with reagent red cells after 37 °C incubation and AHG addition.

Elution

Procedure that removes and recovers antibodies bound to sensitized red cells for further identification.

Autoadsorption

Removal of autoantibody from patient serum by incubating it with the patient’s own treated red cells; permits detection of underlying alloantibodies.

Differential Adsorption

Adsorption of patient serum with selected allogeneic red cells when autologous cells are unavailable, helping separate multiple antibodies.

Enzyme-Treated Cells

Red cells exposed to ficin, papain, or bromelin; treatment enhances Rh, Kidd, P1 and Lewis antigens while destroying M, N, S, Fya/b.

Low-Frequency Antigen

An antigen present in <1% of the population; antibodies to such antigens may be missed in routine screens.

High-Frequency Antigen

An antigen present on >98% of the population’s red cells; antibodies against it can cause panreactivity in testing.

Crossmatch

Compatibility test mixing patient serum with donor red cells to detect serologic incompatibilities prior to transfusion.

Immediate-Spin Crossmatch

ABO compatibility test performed at room temperature, detecting IgM antibodies that cause rapid agglutination.

Antiglobulin Crossmatch

Full 37 °C incubation plus AHG phase to detect clinically significant IgG alloantibodies in recipient serum.

Electronic (Computer) Crossmatch

Computer-validated check of ABO compatibility permitted when patient has a current negative antibody screen and no history of antibodies.

Compatibility Testing

Collective term for recipient ABO/Rh typing, antibody screen, review of history, and appropriate crossmatch of donor units.

Emergency-Release Blood

Group O, D-negative (or D-positive in adults if necessary) uncrossmatched units issued when life-threatening bleeding precludes routine testing.

DTT (Dithiothreitol)

Reagent that destroys IgM pentamers by breaking disulfide bonds; used to differentiate IgM antibodies and to confirm anti-Kp, anti-k, anti-Jsb.

Warm Autoantibody

IgG autoantibody that reacts optimally at 37 °C and AHG phase, often panreactive and requiring adsorption to reveal alloantibodies.

SPRCA (Solid-Phase Red Cell Adherence)

Immunoassay where antigen-coated wells capture antibodies; indicator cells form a layer across the well in positive reactions.

Indicator Cells (SPRCA)

IgG-coated red cells added after serum incubation; they bind to immobilized antibodies, creating adherence that signals positivity.

Gel Technology (ID-MTS)

Testing platform where agglutinated cells are trapped in gel matrix; unagglutinated cells form a pellet at the bottom (negative).

Check Cells

IgG-sensitized red cells added to negative AHG tests to verify adequate washing and active AHG reagent.

Mixed-Field Reaction

Appearance of two distinct red-cell populations in testing, commonly after recent transfusion or stem-cell transplant.

Capture-R Select

Solid-phase microwell assay used for antibody identification panels and antiglobulin testing in automated systems.

TRALI (Transfusion-Related Acute Lung Injury)

Noncardiogenic pulmonary edema within 6 h of transfusion, typically caused by donor anti-HLA/HNA antibodies reacting with recipient neutrophils.

TACO (Transfusion-Associated Circulatory Overload)

Volume overload reaction presenting with dyspnea, hypertension, and pulmonary edema shortly after transfusion.

Febrile Nonhemolytic Transfusion Reaction

Temperature rise ≥1 °C due to recipient antibodies against donor leukocyte antigens or cytokines in the component.

Haptoglobin

Plasma protein that binds free hemoglobin; low levels indicate intravascular hemolysis.

Irradiation of Blood Products

Exposure of cellular components to 25 Gy gamma rays to prevent transfusion-associated graft-versus-host disease (TA-GVHD).

TA-GVHD

Severe, often fatal reaction where donor lymphocytes engraft and attack immunocompromised recipient tissues.

Posttransfusion Purpura (PTP)

Sudden, severe thrombocytopenia 5-12 days post-transfusion due to recipient anti-HPA-1a destroying autologous and transfused platelets.

Hemolytic Disease of the Fetus and Newborn (HDFN)

Fetal/neonatal anemia and hyperbilirubinemia caused by maternal IgG antibodies crossing the placenta and destroying fetal red cells.

Rh Immune Globulin (RhIG)

Concentrated anti-D IgG given to D-negative women to prevent alloimmunization after exposure to D-positive red cells.

Fetomaternal Hemorrhage (FMH)

Transplacental passage of fetal red cells into maternal circulation, assessed to determine RhIG dose.

Kleihauer–Betke Test

Acid elution smear quantifying fetal cells (HbF-rich) resistant to acid, used to estimate FMH volume.

Rosette Test

Qualitative screen for FMH detecting ≥10 mL fetal whole blood by forming rosettes around D-positive fetal cells in maternal sample.

Hydrops Fetalis

Severe fetal edema from profound anemia, often fatal manifestation of HDFN.

Exchange Transfusion

Procedure replacing neonatal blood with donor blood to remove bilirubin and maternal antibodies, and correct anemia.

Plasmapheresis

Therapeutic removal of plasma to eliminate pathogenic antibodies or immune complexes, e.g., in TTP or myasthenia gravis.

Cryoprecipitated AHF

Cold-insoluble fraction of plasma rich in fibrinogen (≥150 mg), factor VIII, vWF, and factor XIII, stored frozen.

Plateletpheresis (Apheresis Platelets)

Collection of ≥3.0 × 10¹¹ platelets from a donor during one procedure, equivalent to 5-6 random platelet units.

Leukocyte-Reduced RBCs

Red-cell units filtered to <5 × 10⁶ leukocytes to reduce febrile reactions, CMV transmission, and alloimmunization.

Frozen RBCs

Glycerol-protected red cells stored at ≤−65 °C for up to 10 years; deglycerolized before transfusion.

Apheresis Granulocytes

Component containing ≥1.0 × 10¹⁰ neutrophils collected for patients with severe neutropenia and infections unresponsive to antibiotics.

Crystalloid Solution

Electrolyte-based fluid (e.g., 0.9 % saline or Ringer’s lactate) used to treat hypovolemia or serve as compatible infusion medium with blood.

Erythropoietin (EPO)

Hormone produced mainly by kidneys that stimulates red-cell production; recombinant form treats anemia of chronic disease.

G-CSF (Granulocyte Colony-Stimulating Factor)

Cytokine that enhances neutrophil production; used to reduce infection risk during chemotherapy and to mobilize stem cells.

Transfusion-Associated Sepsis

Bacterial contamination leading to septic reaction; Yersinia enterocolitica is a notable cold-growing culprit in RBC units.

Yersinia enterocolitica

Gram-negative bacterium thriving at 4 °C; can contaminate RBC units and cause transfusion-transmitted sepsis.

Surrogate Test (ALT)

Alanine aminotransferase assay formerly used to indicate possible hepatitis infection before specific viral assays were available.

HTLV-I/II

Human T-lymphotropic viruses associated with adult T-cell leukemia/lymphoma and tropical spastic paraparesis; screened in blood donors.

ELISA (Enzyme-Linked Immunosorbent Assay)

Immunoassay detecting viral antigens or antibodies; sandwich format gives higher absorbance for positive samples, competitive gives lower.

Western Blot / RIBA

Confirmatory assays for anti-HIV or anti-HCV antibodies, detecting specific viral proteins on nitrocellulose strips.

Universal Plasma Donor

Group AB plasma, lacking anti-A and anti-B antibodies, compatible with recipients of any ABO type.

Type and Screen

Pretransfusion protocol performing ABO/Rh typing and antibody screen; crossmatch deferred unless transfusion becomes necessary.