Chapter 7-The cross-matching-1.ppt

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1. CHPTER -SEVEN
The Cross-Match
(compatibility testing)
CH

2. Content
Cross matching
Types of Cross Match
Steps for compatibility testing
Choice of Blood for cross-match
Procedure for cross-match

3. Learning Objectives
At the end of this chapter, the student will be able
to:
Explain the cross-match and its primary
purpose.
Describe the constituents of the major and minor
cross match.
Select appropriate blood for cross-match.
List the types of antibodies that can be
encountered at various phases of a cross-match.
Perform cross matching

4. 7.1 Cross-Matching
It is a test to determine the compatibility between
recipient’s blood and donor’s blood.
It is a procedure performed before transfusion to
select donor’s blood that will not cause any
adverse reaction, (hemolysis /agglutination)
The test is important to see whether there is
danger or not if the donor’s blood is transfused
to the recipient.
helps the patient to receive maximum benefit from the
transfusion of red cells

5. Cross-Matching…
Main purpose is to prevent a transfusion
reactionthat may result due to:
Unexpected antibodies in the patient’s /donor’s
serum
Some ABO incompatibilities and
Technical or labeling errors (clerical errors)

6. Cross Matching…
Transfusion reaction –is the term used to
describe the clinical effects caused by the
destruction of red cells of recipient by the
donor’s antibodies or a donor’s red cell’s by the
recipient antibodies during an incompatible
transfusion.

7. Cross-matching…
Will not:
prevent immunization of the patient
guarantee normal survival of transfused erythrocytes
detect all unexpected antibodies in a patient’s serum.

8. 7.2 Types of Cross Match
Major and Minor crossmatch
Major cross-match:
involves mixing recipient’s serum with the
donor’s red cells.
is much more critical for assuring safe
transfusion than the minor compatibility test.
called major b/c the Abs in the recipient’s serum
are most likely to destroy the donor’s RBC

9. Types….
Minor cross match:
Involves mixing the donor’s serum with patient’s
red cells
Called minor because
any Ab in the donor’s serum will be diluted by the
large volume of the recipient’s blood
the destructed RBCs of the patient may be
compensated by the transfused RBC of the donors

10. 7.3. Steps for compatibility testing
Accurate Patient Identification
Proper sample collection and handling
Review of the recipient’s past blood bank
records
Careful ABO/Rh determination
Antibody screening of the recipient (cross
matching of the donor unit).

11. Steps for…
In cases when the recipient possess a clinically
significant Antibody, donor units must be:
Screened for the corresponding Ag and should be
negative
Cross-matched

12. Steps for….
Finally, during the actual transfusion :
careful observation of the recipient’s vital signs and
post transfusion hematocrit and Heamoglobin levels
must be considered.

13. 7.4.Choice of Blood for cross-match
The blood selected for cross-match should be of
the same ABO and Rh (D) group as that of the
recipient.
However, Rh positive recipients may receive
either Rh positive or Rh negative blood.

14. Choice of…
Whenever possible blood of the patients own
blood group should be given.
Otherwise the following rules should be applied.
Group A patient.
-Should receive group A blood, if not available group O
Group B patient.
-Should receive group B blood, if not available group O

15. Choice of…
Group O patient.
Can only receive group O blood
Group AB patient.
Should receive from group AB, if not possible can
receive blood from group A,B, and O.

16. Choice of…
When cross-matching is carried out, the serum
is tested against the cells.
The serum should be fresh, that is not more than
48hours old, to make sure that it contains
complement.

17. Choice of…
When deciding on methods for cross-matching,
the following conditions are required for Ag-Ab
reactions.
The right Temperature.
Suitable surrounding medium
Antigen-Antibody ratio etc..

18. Choice of…
The safe cross-matching of blood requires that
the donor’s cells be mixed with the patient’s
serum in three separate tubes, using :
1. Saline
2. Albumin
3. Anti-human globulin reagents

19. 1. Saline tube
The red cells from the donor are suspended in
saline and mixed with the patient’s serum .
show the presence of any complete antibodies
Agglutination in the saline tube is usually caused
by:
anti-A or anti-B antibodies and
Occasionally by Lewis, MNSs, Lutheran and kell
antibodies.

20. 2. Albumin tube
The red cells from the donor’s suspended in
saline, are mixed with the patient’s serum, and
albumin is added.
The tube is incubated at 37
0
C
shows the presence of any incomplete
antibodies
the antibodies react in albumin or any other
protein medium

21. Albumin tube…
Agglutination in the albumin tube is often caused
by:
the rhesus antibodies,
Lewis, MNSs, Lutheran and P antibodies, and
occasionally by anti-kell.
Reaction caused by anti-A or anti-B antibodies
usually occur in albumin as well as in saline.

22. 3. Anti-human globulin tube
A more concentrated suspension of red cells is
mixed with the patient’s serum and incubated at
37
0
C and then AHG is added.
A postive test detects the presence of antibodies
of:
rhesus, kell, kidd, S and Lewis
Anti globulin is essential for detection anti-Duffy

23. 7.5. Procedure for cross-match
7.5.1.Standard cross-match
Is cross-match that is performed in three tubes
(Saline, albumin and AHG) within 45 to 60
minutes
Clinical significance
detects unexpected (irregular) antibodies in the
recipient/ donor serum

24. Cross match (Standard)…
Principle
Serum of the recipient / donor is tested against
the red cells of the donor/ recipient under
different conditions in order to establish their
compatibility

25. Cross match….
Type of specimen
Serum (plasma) not older than 48 hrs
Washed cells (20-30% and 2-5%)

26. Cross match (Standard)…
Equipments and reagents
Test tubes
Centrifuge
Microscope
Microscopic slide
Normal saline
20% albumin
AHG (Coombs reagents)

27. Procedure
1. Take 3 small tubes mark them 1,2 and 3, and
add to each the following
Tube 11volume of patient’s serum
1volume of 3-5% donor’s red cells
Tube 21 volume of 20% bovine albumin
1volume of patient’s serum
1volume of 3-5% donor’s red cells
Tube 3 3 volume of patent’s serum
1volume of 20-30% suspension of
donor’s cells

28. Cross match (Standard)…
2. Incubate tube 1at RT for 30 min and Tube 2 for
30 minutes at 37
0
C. Incubate tube 3 for 15
minutes at 37
0
C.
3. After incubation, remove tube 3 and wash the
cells three times with clean saline to make sure
that all the globulins are removed from the
cells.
4. And make a 3% saline suspension of the
washed cells in a tube.

29. Cross match (Standard)…
5. To one volume of red cell deposit add 2
volumes of fresh diluted antiglobulin (coombs)
Reagent.
6. Remove tube 1 and 2 and centrifuge with tube 3
for one minute at 1000 rpm
7. Examine the tube for heamolysis
macroscopically and microscopically for
agglutination.

30. Cross match (Standard)…
Results
No hemolysis or agglutination is seen in tube 1,
2 or 3
the blood is compatible and can be issued with the
completed cross-match label.
If there is agglutination or hemolysis in any of
the tubes
the blood is incompatible, and must not be issued for
the patient.

31. Incompatibility investigation
ABO incompatibility (anti A and Anti-B.)
Saline tube ………………….Shows strong agglutination
Albumin tube ………………. Shows agglutination
Anti-globulin tube ………… show no agglutination
Rhesus incompatibility (anti-D ,c, e)
Saline tube …………………….does not usually show
agglutination
Albumin tube …………………. Shows agglutination
Anti-globulin tube ……………. Shows agglutination

32. Cross match (Incomp. Invest.)…
Anti-Duffy and anti-kidd incompatibilities
Saline tube …… Does not usually show agglutination
Albumin tube … does not usually show agglutination
Anti-globulin tube ……………. Shows agglutination
Anti-Lewis incompatibility
Saline tube …………………….. Shows agglutination
Albumin tube ………………….. Shows agglutination
Anti-globulin tube ……………. Shows agglutination

33. 7.5.2 Emergency cross match
Performed when there is no enough time to
perform the standard cross match
Takes about 25 to 30 minutes and
Does not include antiglobulin test.

34. Cross match (Emergency)…
Principle
Serum of the recipient / donor is tested against
the red cells of the donor/ recipient in saline and
albumin medium in order to establish their
compatibility

35. Cross match (Emergency)…
Type of specimen
Serum (plasma) not older than 48 hrs
Washed cells (2-5%)

36. Cross match (Emergency)…
Equipments and reagents
Test tubes
Centrifuge
Microscope
Microscopic slide
Normal saline
20% albumin

37. Procedure:
1.Take 2 small tubes, mark them 1 and 2 and
add to each the following
Tube 1 1volume of patient’s serum
1volume of 3-5% donor’s red cells
Tube 2 1volume of patient’s serum
1volume of 3-5% donor’s red cells.
1volume of 20% bovine albumin

38. Cross match (Emergency)…
2. Leave tube 1 at room temp for 15 minutes
incubate tube 2 for 15 minutes at 37
0
C.
3. Centrifuge both tubes for one minute at 1000
rpm/min
4. Examine the tubes macroscopically for
hemolysis and microscopically for agglutination.

39. Cross match (Emergency)…
Results
If no hemolysis or agglutination is seen in either
tube 1 or 2
the blood is compatible and can be issued with the
emergency cross match.
If agglutination or hemolysis is seen in either of
the tubes
the blood is incompatible and must not be issued for
the patient.

40. 7.5.3. Rapid direct slide cross match
(Request for un cross matched blood )
Takes only 3 or 4 minutes
Plasma is used instead or serum.
Not safe and must only used in extreme
emergencies
Standard cross match should be carried out
while the transfusion is in progress.

41. Procedure
1.Take 2 volume of patient’s plasma on a slide
2.Add 1 volume of donor’s whole blood of the
same group as the patient and mix.
3.Leave for 2 minutes and examine
microscopically for agglutination

42. Cross match (Rapid)…
Results
If the cells show agglutination the blood must not
be given and will usually indicate that the wrong
ABO group blood is being cross marched.

43. Cross match (Rapid)…
Sources of errors in cross-matching
Rouleaux
Auto agglutinins
Infected donor cells
Anti-A1
Over centrifugation
Dirty glass wares etc..

44. Review Questions
1. What is cross-matching?
2. What is the purpose of cross-matching?
3. List the types of cross-match with their
constituents
4. List the stages of cross-match and their
respective importance in antibody detection.

45. References
1.Immunohematology for medical laboratory
science students,Yayehyirad T. and Misganaw
B., Upgraded lecture note.2008
2.Basic and applied concepts of
Immunohematology, 2
nd
ed. Kathy D.Blaney
and Paula R.Howard,2009
3. Blood banking and transfusion medicine: basic
principles and practice. Christopher D.Hilliyer et
al., 2
nd
ed.2007.
4.Safe blood donations, Module 1 WHO.2002
45

46. References…
5.Screening for HIV and other infectious agents,
Module 2, WHO. 2002
6.Blood group serology. Module 3 WHO.2002
7.Guidelines and principles for safe blood
transfusion practice, Introductory module. WHO
2002.
8.Immunohematology: Principles and Practice
Quinley. 2nd ed.1998.
9.AABB Technical Manual .15th Edition.2005
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