Testing with both Anti-A and Anti-B is necessary to determine if red blood cells possess or lack A and/or B blood group antigens.

Absence of agglutination is a negative test result, which indicates the corresponding antigen is not demonstrable.

Agglutination of red blood cells with a given reagent is a positive test result, which indicates the presence of the corresponding antigen on the red blood cells. (Forward Type)

Direct agglutination of A1 or B reagent red cells with the patient serum/plasma indicates the presence of the appropriate ABO antibody. (Reverse type)

Forward and reverse typing will be performed on samples for all patients greater than four months of age to allow for discovery of subtypes as well as to confirm typing. Individuals less than four months old may not have developed sufficient antibody to allow for detection.

Pre-transfusion testing ensures compatibility between the transfusion patient and the blood component(s) (red blood cells, platelets, plasma) intended for transfusion.

This process includes accurate and thorough completion of the requisition, accurate patient identification, proper collection and labelling of the blood sample from the patient, laboratory testing to determine the patient’s blood group and to identify the presence of red blood cell alloantibodies, and compatibility testing.

Pre-transfusion testing ensures compatibility between the transfusion patient and the blood component(s) (red blood cells, platelets, plasma) intended for transfusion.

This process includes accurate and thorough completion of the requisition, accurate patient identification, proper collection and labelling of the blood sample from the patient, laboratory testing to determine the patient’s blood group and to identify the presence of red blood cell alloantibodies, and compatibility testing.

• Blood Grouping Reagent: Anti-A and Anti-B (forward cells)
• Reagent red blood cells: A1 and B cells (reverse cells)
• Test tubes (12 x 75 mm)
• Pipettes
• Physiologic Saline
• Timer
• Centrifuge
• Optical Aid with Light

Forward Typing

1. Prepare a 3-5% suspension of red blood cells to be tested in isotonic saline. (Washed or unwashed cells may be used.)
2. Place 1 drop of Anti-A and Anti-B respectively, in two small, properly labeled test tubes.
3. Add one drop of rbc suspension into the tube and mix.
4. Centrifuge the test tube for appropriate centrifuge time.*
5. Completely resuspend cells and examine macroscopically for agglutination. Note: Hemolysis may be a consequence of bacterial contamination and should not be interpreted as a positive result.
6. Grade and record results.

Reverse Typing

1. Label a test tube for each rbc reagent to be tested. (A1 or B).
2. Place two (2) drops of the serum/plasma into each labeled tube.
3. Add one (1) drop each of A1 cells and B cells to the appropriate tube.
4. Mix gently. Centrifuge the test tubes for appropriate centrifuge time.*
5. Completely resuspend cells and examine macroscopically for agglutination.
6. Grade and record results.