Compatibility testing is a collection of different processing; a series of testing procedure and processes with the ultimate objective of ensuring best possible result of a blood transfusion
Strict adherence to and application of each parameters of compatibility is imperative to the management of safe blood transfusion.
ABO/Rh is the foundation of compatibility testing.
If you’re donor and recipient are not match, there is no sense of continuing compatibility testing
Serological crossmatch phases:
Immediate spin or saline phase
37°C or Thermophase
AHG phase
Major Crossmatch is routinely perform in laboratory
Patient serum + Donor Red Cell
Generalized antibody screening – what antibody is present.
We look for antibodies against donor red cell
Minor Crossmatch is widely replace by antibody screening
Antibody screening or alloantibody identification looks for alloantibody in the patient serum or plasma
We can identify antibodies present in the patients serum that could potentially react with your donor red cells
Clerical error is the major cause of transfusion associatedfatalities (greatest test)
Common causes of errors:
Misidentification of recipient – pre-analytical error
Mix-up of samples during processing – analytical error
Misidentification of recipient when transfusion is given – post-analytical error
Patient’s wristband ID must always be compared to requisition form
Ideally, serum is the preferred sample for blood bank
Incompatible crossmatch is indicated by agglutination and that means that there is antibodies against the red cell → can be seen in serum or plasma.
Hemolysis is a false positive error
Patient with hemolytic anemia is not rejected
Samples in BB are usually in red top tube because tubes with clot activators might contaminate the serum and can cause false agglutination.
In blood bank, tubes used are:
Purple / lavender EDTA - is used in hematology section
Pink EDTA – is specific for blood bank
Donor sample must be collected at the same time as the full donor unit
Donor information/medical history card, pilot samples and collection bag must be labeled with the same unique numbers before starting the phlebotomy
RBCs for donor pre-transfusion testing can be prepared from segmented tubing through which donor blood was collected
Using a heat sealer, we segment the tube and each segment can be used for testing.
Note: donor and recipient samples must be stored for a minimum of 7 days post transfusion (stoppered, labeled 1-6°C) in relation to transfusion reaction