1. Antibody Screening / Detection & Antibody Identification
S. Nasizadeh, APCP
DiaMed Switzerland

2. “Direct Transfusion”

3. SHOT REPORT: IBCT Vs TTD
ABO incompatibilities 9.5%
RhD incompatibilities 6.3%
Other blood group antigens 6.3%
TOTAL IBCT %
HIV %
HBV %
HAV %
Malaria %
Bacterial contamination %
TOTAL TTDs %

4. Ab screening Ab identification
Compatibility Testing
Ab screening
Indirect Antiglobulin Test
2 or 3 red blood cells
To detect ANY clinically significant Ab
Ab identification
11 reagent panel cells
To detect THE clinically significant Ab

7. Unexpected Antibodies (Non-A, Non-B)*
Unexpected Antibodies (Non-A, Non-B)
Found in:
Chronically transfused patients
Pregnancy
Transplants
Needle sticking

8. Clinically Significant Antibodies.*
Clinically Significant Antibodies.
Clinically significant antibodies in vitro are detected by the indirect antiglobulin technique (IAT) at a strict 37ºC.

9. *
Antibody Screening
The antibody screen is a serological technique designed to detect the presence of ANY clinically significant antibody(ies) present in patient’s blood sample.

10. Antibody Screening, Indications
For detection of irregular antibodies (non-ABO)
Pre-transfusion tests
Antenatal screening
Donor units
HDN

11. Antibody screening procedure
Two cell pooled (only for donors)
Two cells (not pooled)
Three cells (recommended)

12. Antibody Screening

13. * Antibody Screening Allow the early detection of antibodies.
Enable laboratories to phenotype available units, or obtain appropriate antigen negative blood from their Blood Centre.
Negate the need for serological crossmatching if the screen is negative. C/T ratio = 2/1
VERY IMPORTANT

14. Antibody Identification
If the Antibody Screen is reactive, the antibody specificity must be determined.
So safe blood can be administered to the Recipient.
11 reagent panel cells are to be used for identification.

15. Antibody Identification*
Antibody Identification
The antibody identification is a serological technique designed to determine the TYPE of the clinically significant antibody(ies) present in patient’s blood sample.

16. Antibody Identification

17. Antibody Identification.*
Antibody Identification.
When an antibody is detected in the antibody screen, crossmatch compatible blood should not be issued until:
The antibody has been positively identified
and
If the antibody is clinically significant, units phenotyped and found antigen negative for the appropriate antibody have been obtained.

18. *
Antibody Exclusion
Antibody exclusion is an important part of antibody investigative work and should always be performed.
It is essential that when one antibody has been identified, the potential presence of another, masked, antibody has not been overlooked.

19. Antibody Screening / Identification

20. Antibody Specificity (confirmation)*
Antibody Specificity (confirmation)
Current pre-transfusion guidelines state:
‘The specificity of the antibody should only be assigned when it is reactive with at least two examples of reagent red cells carrying the antigen and non-reactive with at least two examples of reagent red cells lacking the antigen’ .
In order to meet this criteria, more than one identification panel may be necessary.

21. Advatages of cross matching (XM)
Easy,
Routinely applied in all blood banks
Relatively cheap

22. Disadvantages of cross matching
Missing of some weak antibodies
Compatible XM may still cause hemolytic reactions
Time consuming in cases of incompatibility

23. Advantages of antibody screening
Detection of weak antibodies (homozygous cells)
Preparation and testing of blood at leisure
Batch and mass testing
Automation
Substitution of cross matching (in optimal conditions)

24. Antibody screening Requires : - Training interpretation skills - Time
- Tomans

25. Price / Time comparisonXM
RT + 37 AHG (2 tubes)--- 2x
Repeat incompatibles, e-g 4 units --- 8x
4 x 30 min= 120 min
Ab Screen
2 x 37 C tubes (2x)
Or 3 x 2 (AHG +ENZ)= 6x
30 min

26. *
Tests Are Performed to Provide Compatible Blood With the Minimum Delay.
The red cells will have the maximum survival following the transfusion.
The donor’s blood will not cause an adverse reaction.
Serological compatibility cannot guarantee that an antibody will not cause a transfusion reaction.