Pre-Transfusion Blood Tests

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  • Topic: Coombs test, Blood type, Hemolytic anemia
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Pre-transfusion Blood Tests:

Title: To perform the following tests:
ABO and RH grouping using the Diamed Gel Card system.
Rh and Kell phenotyping (antigen typing) using the Diamed Gel Card system. Direct Coombs Test (DCT) using the conventional tube system. Direct Coombs Test (DCT) using the Diamed Gel Card system. Antibody Identifications (IAT) technique using the conventional tube system. Antibody Identifications (ETC) technique using the Diamed Gel Card system.

Name: S. Ward

Date: 8/11/2012

Introduction:
The objective of this practical is to perform some pretransfusion tests, using various methods. Pretransfusion testing is carried out in all hospital blood bank laboratories and is used to minimise the risk of encurring a haemolytic transfusion reaction. Haemolytic transfusion reactions occur when a patient is transfused with red cells which have a foriegn antigen on the cell surface that the patient has an antibody to. While the ABO and Rh blood group systems are the most antigenic and thus can cause severe haemolytic transfusion reactions. The other blood group systems can also cause a (less severe) haemolytic reaction, these reactions can be fatal and so the procedures to avoid them are of great importance.

Materials & Method:
Not all tests were performed by all members of the class.
ABO and Rh blood grouping using the Diamed Gel Card system; performed. Rh and Kell trying using the Diamed Gel Card system; not performed. Direct Coombs Test (DCT) using the Diamed Gel Card system;not performed. Antibody Identification (ETC) technique using the Diamed Gel Card system; performed but not centrifuged so no results were obtained. Antibody Identifications (IAT) technique using the conventional tube system; performed Direct Coombs Test (DCT) using the conventional tube system; performed.

Cell 1% suspensions were prepared for the bench from a 3% cell suspension provided.

Results:
As well as some tests not being completed by everyone, some results were not obtained as there was a queue for the ID centrifuge. Results below are ones obtained by myself;

ABO & Rh grouping;
Known O+ cells were tested. Expected results would be;
However, the gel matrix had dried out so no results were obtained.

Antibody Identifications (IAT) technique using the conventional tube system; +
+
+
-
-
+
-
-
+
+

When these results are compared with the ID panned profile, its is seen that there is no antigen which matches the antibody in the patient's plasma.

Traditional Direct Coombs test results was positive.

Discussion:
The results from this practical were not as expected.
With regard to the ABO Rh typing, the expected result for the O+ blood tested is as shown above. The reason why the results obtained were incorrect were because the gel had dried out. This shows that it is very important to ensure that the reagents used in the transfusion laboratory are of a really high quality to ensure that all results obtained are reliable. With regard to the traditional antibody profile, it is seen that there is no antigen which matches the antibody in the patient's plasma according to the ID panel. It is possible that the patient has an uncommon antigen which isn't on the ID panel. However, it's more likely that there was human error in labelling the reaction tubes 1-10. The direct coombs test checks to see in vivo sensitisation to IgG antibodies. The traditional coombs test results for this practical showed aggultenation when treated with antihuman globulin, which is a positive result. Results for the other laboratory tests using Diamed Gel Card system were unobtained due to there being a queue for the centrifuge.

A brief explanation of all these tests is explained below;
ABO & Rh D grouping; this can be done by conventional tube technique, as performed previously, or can be done using the Diamed Gel Card system. These gel...
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