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Pushing all boundaries
CROSS MATCH TESTING
Crossmatch is a test that verifies the compatibility of the donor and recipient in terms of products containing red blood cells and plasma.
The crossmatch test is not intended to replace the blood typing test but to supplement it. Combining the crossmatch test and the blood typing test ensures a higher percentage of certainty that the donor and recipient have compatible blood groups and significantly reduces the likelihood of any allergic reaction when administering the product (but not completely).
To perform a crossmatch test, there are commercial kits on the market, but it is also possible to perform the test using existing means in any clinic which costs less than the kits.
The crossmatch test is divided into two types according to the product that will be given to the donor.
- Major Crossmatch test - used before giving a dose of blood concentrate or whole blood.
- Minor Crossmatch test - used before giving a dose of plasma or whole blood to the donor. It is important to note that the minor crossmatch is less important than the major crossmatch, because after the plasma is transfused to the donor, its concentration (and the concentration of protein elements in it that may lead to an undesirable reaction in the donor) decreases significantly as a result of natural dilution about the donor's blood volume.
Minor Crossmatch
In the Minor Crossmatch test, the donor's red blood cells are tested against the donor's plasma. To perform the test, the following steps must be followed:
1. Collect blood from the donor into two EDTA tubes (tubes B and C), At the same time, disconnect a sample tube from the plasma portion and empty the contents into an empty tube free of any anticoagulant (tube A).
2. Centrifuge both tubes (of the donor) at 1000X9 for 5 minutes.
3. Leave only the sediment of red blood cells by separating the plasma from one of the donor tubes (tube B) and leave the other as is (tube C, control).
4. Wash tube B with 0.9% saline three times, and finally make 4% mixtures (1 drop of donor blood to 20 drops of 0.9% saline) in a new tube without anticoagulant (tube D), three-quarters full.
5. Add two drops of plasma (donor, from tube A) to each drop of blood (donor, from tube D), three-quarters full. tube.
6. Mix tube E gently and allow to stand at room temperature for 15 minutes.
7. Centrifuge tube E again at 9X1000 for 15 seconds only.
Check possible results in tube E:
Is hemolysis present by macroscopic examination of the tube
Shake the tube gently to cause the blood sediment to float and examine macroscopically for obvious agglutination.
Perform microscopic examination to diagnose agglutination
Check the control.
Major Crossmatch
In the Major Crossmatch test, the donor plasma is tested against the donor's red blood cells. To perform the test, follow these steps:
1. Collect blood from the donor into two EDTA tubes (tubes II and III), at the same time, disconnect a sample tube from the blood concentrate and empty its contents into an empty tube that is free of any anticoagulant (tube I).
2. Centrifuge both tubes (of the donor) at a speed of 1000X9 for0.9% in tube I (donor), about three times, and finally create 4% mixtures (a drop of donated blood to 20 drops of 0.9% saline) and transfer the mixture to a new tube without anticoagulants (tube V).
5. Add to a new tube empty of all anticoagulants (tube VI) two drops of plasma (donor, tube IV) for each drop of blood (donor, tube V) until the tube is three-quarters full.
6. Mix tube VI gently and let stand at room temperature for 15 minutes.
7. Centrifuge tube VI again at a speed of 9X1000 for 15 seconds only.
Check possible results in the VI test tube:
Is hemolysis present on macroscopic examination of the test tube?
Shake the test tube gently to float the blood sediment and examine macroscopically for obvious agglutination.
Perform microscopic examination to detect agglutination
Check the control
