Higher Blood Types and Transfusions

Higher Blood Types and Transfusions

ABO Blood Group System

Blood types are determined by antigens on red blood cell surfaces:

• Type A: A antigens on red blood cells; anti-B antibodies in plasma
• Type B: B antigens on red blood cells; anti-A antibodies in plasma
• Type AB: Both A and B antigens; no antibodies (universal recipient for red cells)
• Type O: No antigens; both anti-A and anti-B antibodies (universal donor for red cells)

If incompatible blood is transfused, the recipient's antibodies bind to the donor's antigens, causing agglutination (clumping) of red blood cells. This can block blood vessels and is potentially fatal.

Rhesus Factor

• Rh positive: Have the Rh antigen on red blood cell surfaces (approximately 85% of the UK population)
• Rh negative: Lack the Rh antigen
• Clinical importance: Critical for blood transfusion compatibility and in pregnancy — if an Rh-negative mother carries an Rh-positive fetus, she may produce anti-Rh antibodies that attack subsequent Rh-positive pregnancies