ABO Grouping

To determine the particular ABO blood group of a sample of blood, the forward and reverse grouping tests are performed.
In the forward grouping test, the patient's RBCs are mixed with reagent anti-A and anti-B antisera. Agglutination indicates a positive test.
In the reverse grouping test, the patient's plasma is mixed with reagent A and B RBCs. Again, agglutination indicates a positive test.