Biology
How to Identify Blood Groups
Everyone belongs to one of four main blood groups, A, B, AB or O, and is also Rh positive (+) or Rh negative (−). Together these make eight blood types. A group is decided by antigens, which are markers on the surface of red blood cells.
Antigen + matching antibody → red cells clump together (agglutination)
To find a blood group, a laboratory mixes drops of blood with three test liquids called anti-A, anti-B and anti-D. Clumping shows which antigens are present. This is a classroom model. Real blood typing is done by trained laboratory staff.
- Learn the antigens and antibodies of each group.
- Add blood to the three test wells.
- Read the reactions.
- Name the blood group.
- Choose safe blood donors for the patient.