Question

What tests need to be performed, if DAT is positive on a post-transfusion/pre-transfusion blood sample? What baseline and follow-up testing are useful in identifying the cause of the adverse reaction?

Answer 1

Direct antiglobulin test is also called as Coombs test used to determine the presence of antibodies on the RBC

A positive DAT in pre-transfusion /post -transfusion blood sample indicates the presence of antibodies on RBC (When a person receive blood, the antigen present in the donar RBC are recognised by the recipient's antibodies and this sticks on them.The DAT is used to find this antibodies )

When this test is positive, the following base line and follow up test are used to identify the cause of adverse reactions are as following

• CBC to get the baseline status of the patient
• Cross matching and grouping to confirm the reactions due to transfusion
• Urine test to determine the presence of RBC due to hemolysis
• Antibody screening
• Liver profile to know the changes in the bilirubin level
• Clotting factors to assess tge risk of bleeding