ABO Grouping There are two methods for ABO grouping: Cell grouping (forward grouping): Red cells are tested for the presence of A and B antigens employing known specific anti-A and anti-B (and sometimes anti-A, B) sera. Serum grouping (reverse grouping): Serum is tested for the presence of anti-A and anti-B antibodies by employing known group A and group B reagent red cells. Both cell and serum grouping should be done since each test acts as a check on the other. There are three methods for blood grouping: slide, tube and microplate. Tube and microplate methods are better and are employed in blood banks. Further Reading: DETERMINATION OF BLOOD GROUP BY SLIDE METHOD DETERMINATION OF BLOOD GROUP BY TUBE METHOD MICROPLATE TECHNIQUE FOR RH D GROUPING FALSE REACTION IN ABO GROUPING Rh D GROUPING METHOD