If hives are the only symptom reported, the reaction investigation can be completed with only a clerical check. In all other cases, a post-transfusion blood sample must be sent to the laboratory for transfusion reaction investigation.
The initial laboratory investigation of a transfusion reaction is designed to rule-out acute hemolysis and includes all of the following:
- A clerical check, which includes examination of patient identification, blood unit labels, and all pre-reaction records for possible errors in patient or blood identification at the bedside and in the laboratory
- Observation of the pre-reaction (if available) and post-reaction serum/plasma for evidence of hemolysis (as shown in the image on the right)
- Direct antiglobulin test (DAT) and ABO on the post-reaction (recipient) specimen
If all of the above are negative, a hemolytic reaction can be ruled out. If any of these screening tests are positive, additional testing is required.