Testing the Patient Serum with Known Red Cells (Reverse Typing)

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The page below is a sample from the LabCE course Introduction to the ABO Blood Group System. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

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Testing the Patient Serum with Known Red Cells (Reverse Typing)

Antibodies occur predictably in the sera of all normal adults in association with the ABO antigens. Demonstration of these antibodies is necessary for definitive classification of an individual's ABO cell type. The individual's serum is therefore tested against reagent red cells containing known antigens (see Table 3). This is called reverse typing.
Table 3. Testing the Patient Serum with Known Red Cells (Reverse Typing).
ABO Blood GroupPatient Serum Tested with Known Reagent Cells
A CellsB Cells
A
0
3–4+
B
3–4+
0
O
3–4+
3–4+
AB
0
0
+ = agglutination (graded 1+ to 4+); 0 = no agglutination or hemolysis