1. lecture 10 blood bank Compatibility Testing
Dr. Dalia Galal

2. What is compatibility testing?
Also called pretransfusion testing
Purpose:
To select blood components that will not cause harm to the recipient and will have acceptable survival when transfused

3. Compatibility testing?
There are several components of compatibility testing
Proper specimen collection
Reviewing patient transfusion history
ABO, Rh, and antibody testing (screen/ID)
Crossmatching
Actual transfusion

4. Compatibility testing
Can be divided into 3 categories:
Preanalytical procedures
Serological testing
Postanalytical procedures

5. 1- Pre-analytical phases
Patient and sample identification
Specimen collection
Review of patient history

6. A- Patient and sample Identification
Full patient name and hospital number
Name of physician
Date and time of collection
All of this should be on the request form and the sample

7. Specimen Tubes
Pink Top - EDTA
Red Top – no additives

8. B- Specimen Collection
Collected in tube with EDTA or no additives
If the venipuncture causes hemolysis, the sample may be rejected
True hemolysis in the patient is the result of complement activation
Testing should be performed on samples less than 72 hours, otherwise, complement dependent antibodies may be missed (complement can become unstable)

9. C- Review of patient history
Look at recipient’s records for any prior unexpected antibodies
Previous transfusion reactions

10. 2- Serological Testing ABO/Rh Antibody detection/identification
3 tests:
ABO/Rh
Antibody detection/identification
Crossmatch

11. ABO/Rh Typing In the ABO typing, the forward and reverse MUST match
In the Rh typing, the control must be negative
Both of these will indicate what type of blood should be given

12. Antibody screen and/or ID
The antibody screen will detect the presence of any unexpected antibodies in patient serum
If antibodies are detected, identification should be performed using panel cells (with an autocontrol)
If an antibody is present, units negative for the antigen must be given (remember the calculation?)
Proceed to the cross match…

13. Crossmatching Purpose: Prevent transfusion reactions
Increase in vivo survival of red cells
Double checks for ABO errors
Another method of detecting antibodies

14. Crossmatch Crossmatch Two types of crossmatches
Major – routinely performed in labs
Minor – not required since 1976
Crossmatch
No agglutination ~ compatible
Agglutination ~ incompatible
Donor RBCs (washed)
Patient serum

15. Units of whole blood with segments attached

16. Procedure ABO/Rh typing is FIRST performed
With anti-A, anti-B, anti-D
With A1 cells and B cells
Antibody Screen is performed next
With screening cells

17. Crossmatch Procedure
If antibodies are NOT detected (in antibody screen test):
Only immediate spin (IS) is performed using patient serum and donor blood suspension
This fulfills ABO incompatibility
This is an INCOMPLETE CROSSMATCH
If antibodies ARE detected (in antibody screen test):
Antigen negative units found and X-matched
All phases are tested: IS, incubate at37°, antihuman globulin (AHG)
This is a COMPLETE CROSSMATCH

18. Will Not (disadvantages)
Crossmatches…
Will (advantages)
Verify donor cell ABO compatibility
Detect most antibodies against donor cells
Will Not (disadvantages)
Guarantee normal survival of RBCs
Prevent patient from developing an antibody
Detect all antibodies
Prevent delayed transfusion reactions
Detect ABO/Rh errors

19. Incompatible crossmatches
Antibody screen
Crossmatch
Cause
Resolution
Pos
Neg
Antibody directed against antigen on screening cell
ID antibody, select antigen negative blood
Antibody directed against antigen on donor cell which may not be on screening cell OR donor unit may have IgG previously attached
ID antibody, select antigen negative blood OR perform DAT on donor unit
Antibodies directed against both screening and donor cells
Antibody ID, select antigen negative blood

20. Post-analytical phase
Involves labeling, inspecting, and issuing the blood unit
Labeling form includes patient’s full name, ID number, ABO/Rh of patient and unit, donor #, and compatibility results.
Form is attached to the donor unit and only released for the recipient
The unit is visually inspected for abnormalities, such as bacterial contamination, clots, etc

21. Bacterial contamination
This unit shows bacterial contamination and should NOT be given to the patient
The plasma in the samples is fine, but the plasma in the unit shows heavy hemolysis from bacteria

22. Issuing blood
When it’s time to release a blood product to the nurse or physician, a few “checks” must be done
Requisition form
Comparing requisition form  donor unit tag  blood product label
Name of persons issuing and picking up blood
Date and time of release
Expiration date

23. What if the unit is unused?
Blood can be returned if it is not needed for transfusion
Unit closure has to remain unopened
Storage temperature must have remained in the required range (1° to 10°C for RBCs)
If not at correct temp, unit must be returned within 30 minutes of issue