Which blood type is the universal donor for red blood cell transfusions?

Which blood type is the universal donor for red blood cell transfusions?

• A. O Negative
• B. O Positive
• C. AB Positive
• D. A Negative

Answer: (A)

When matching red blood cells for transfusion, compatibility comes from the presence or absence of A, B, and Rh (D) antigens on the donor cells. O negative blood lacks all three: it has no A or B antigens and is Rh negative. Because it presents no A, B, or D antigens, the recipient’s antibodies are unlikely to recognize and attack those cells, making O negative suitable for transfusion to patients of most ABO and Rh types, especially when the patient’s blood type is unknown or time is critical. This is why O negative is considered the universal donor for packed red blood cells. In contrast, others carry A or B antigens and/or the Rh antigen, which means they can provoke an immune reaction if given to a patient who does not have matching antigens. AB positive, for example, has both A and B antigens and Rh positive, so it is not a universal donor.

When matching red blood cells for transfusion, compatibility comes from the presence or absence of A, B, and Rh (D) antigens on the donor cells. O negative blood lacks all three: it has no A or B antigens and is Rh negative. Because it presents no A, B, or D antigens, the recipient’s antibodies are unlikely to recognize and attack those cells, making O negative suitable for transfusion to patients of most ABO and Rh types, especially when the patient’s blood type is unknown or time is critical. This is why O negative is considered the universal donor for packed red blood cells.

In contrast, others carry A or B antigens and/or the Rh antigen, which means they can provoke an immune reaction if given to a patient who does not have matching antigens. AB positive, for example, has both A and B antigens and Rh positive, so it is not a universal donor.