Forward (Cell) Grouping
Reverse (Serum) Grouping
Category: Unexpected reaction in forward grouping.
Most probable ABO type: Group A
Possible Causes: A(B) phenotype, patient cells coated with IgG, acquired B antigen.
Some strategies for resolution: Retype with monoclonal reagents made from another clone or human polyclonal reagents if available; perform an antibody screen to detect autoantibody; perform a direct antiglobulin test (DAT); or wash patient cells and retest.
Testing patient plasma with patient red blood cells
Patients who are truly group A, without any true B antigen, will demonstrate a negative auto control. Since there is no B antigen present on the patient's red cell and there is anti-B in patient plasma, no agglutination should form.
|A antigen (No B antigen)|| Anti-B|| Negative|