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Table 2: Testing the Patient Red Cells with Known Antisera (Forward Typing)

In routine practice, specially prepared blood grouping sera containing anti-A, anti-B, (and optionally anti-A,B) are used to identify the four types of red cells. These sera will agglutinate cells with the corresponding antigen. This is called forward typing.

ABO Blood GroupPatient Red Cells Tested with Known Antisera
Anti-AAnti-BAnti-A,B

A

3-4+

0

3-4+

B

0

3-4+

3-4+

O

0

0

0

AB

3-4+

3-4+

3-4+

+ = agglutination (graded 1+ to 4+)
0 = no agglutination