Principle of Determination of Blood Group of an Individual - QS Study
QS Study


Blood group is determined by mixing an individual’s Red Blood Cell with anti-serum containing antibody on the slide and observing whether agglutination occurs or not. The test is essential if you need a blood transfusion or are planning to donate blood. Not all blood types are compatible, so it’s important to know your blood group.

Procedure- A blood sample is needed. The test to determine your blood group is called ABO typing. Your blood sample is mixed with antibodies against type A and B blood.

(i) At first, RBCs are separated from the plasma and diluted with isotonic saline.

(ii) 3 drops of the saline are taken on a slide at different drops.

(iii) Then –

  • One portion is mixed with Anti-A Antigen
  • Another portion is mixed with Anti-B Antigen
  • The remaining portion with Anti-D.

People with type A blood have anti-B antibodies. People with type B blood have anti-A antibodies. Type O blood contains both types of antibodies.

Tab: Determination of Blood Group

Here, (+) = Agglutination and (-) = No agglutination


  • If agglutination occurs in 1st case = Blood group A
  • If agglutination occurs 2nd case = Blood group B
  • If agglutination occurs in both cases = AB group
  • No agglutination occurs = O Group
  • Agglutination in 3rd case = Rh + ye
  • No agglutination in 3rd case = Rh – Ve