Blood type

A classification of blood based on inherited antigens on red blood cells. Blood types guide transfusion compatibility and other medical decisions.

Red blood cell: A blood cell that carries oxygen using hemoglobin and displays surface molecules, including blood-group antigens. Blood types classify inherited markers displayed on these cells.
Blood transfusion: The transfer of blood or blood components into a person's circulation. Matching donor and recipient blood types helps prevent immune reactions.
Agglutination: The clumping of cells or particles when antibodies bind targets on their surfaces. Antibody binding can visibly clump incompatible red cells during testing.
Universal donor: An informal description for a donor type suitable for many recipients under specified transfusion conditions. The label is useful shorthand, but no red-cell type is universally safe in every situation.
Blood group genotyping: The analysis of DNA variants to predict a person's red-cell blood-group antigens. Genotyping can resolve complex or uncertain blood types more precisely.
Antigen: A molecule or molecular structure recognized by antibodies or immune-cell receptors. Blood-group antigens are the inherited markers used to classify red cells.
Cross-matching: A pretransfusion test that checks whether a donor's red cells are compatible with a recipient's plasma. It tests compatibility beyond relying on blood-type labels alone.
Hemolysis: The rupture or destruction of red blood cells, releasing their contents into surrounding fluid. Severe incompatibility can trigger destruction of transfused red cells.
Universal recipient: An informal description for a recipient type able to receive red cells from many ABO groups under specified conditions. This shorthand still depends on Rh status, testing, and clinical context.
International Society of Blood Transfusion blood group systems: The internationally recognized catalog of blood-group systems and their antigens. Its expanding catalog shows how much variation lies beyond routine typing.

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