Blood Groups Explained
The familiar blood groups are based mainly on the ABO system and the RhD antigen. Explore each of the eight commonly referenced ABO/Rh combinations below.
A Positive (A+)
A blood group with RhD-positive status.
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A Negative (A−)
A blood group with RhD-negative status.
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B Positive (B+)
B blood group with RhD-positive status.
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B Negative (B−)
B blood group with RhD-negative status.
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AB Positive (AB+)
AB blood group with RhD-positive status.
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AB Negative (AB−)
AB blood group with RhD-negative status.
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O Positive (O+)
O blood group with RhD-positive status.
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O Negative (O−)
O blood group with RhD-negative status.
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Important: blood-group matching
Blood-group compatibility depends on the blood component being transfused. The compatibility information on these pages focuses on red-cell transfusion. Hospitals and blood services perform blood-group testing and compatibility testing before transfusion.
Medical information notice
These pages provide general educational information. They are not a substitute for compatibility testing or medical advice from a qualified transfusion service.