Blood Bank: Tests and Methods

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Blood bank

Although there are any complicated instruments in the blood bank department, but it’s a very important and sensitive section of the medical laboratory as it deals with donors and acceptors of the blood, it transfer for leukemia and thalasemia patients, new born and cancer patients and so many cases blood bank save their lives.

Tests that are carried in this department:
1- Some tests, which included donated free of diseases, serology tests 2- blood grouping
3- rhesus factor"Rh"
4- direct & indirect coombs test
5- cross matching

1-serology tests
To ensure that donated free of infectious diseases as HIV, Hbs, VDRL These tests are rabid tests using a card
2- blood grouping
Red blood cells contain on their surface on Ag A,B, and the have their antibodies in the serum on the same red blood cells. That means, that every blood group can give a specific other group and receive also from a specific one in order to avoid agglutination and so blood clotting.


Method 1:
On a slide put two drops of blood-
-Add a drop of anti A on the first blood drop, and a drop af anti B on the second blood drop - mix and wait for 2 minutes
- observe the agglutination
- if happened with anti A the blood group is A
You can use a test tube instead of the slide, and then put the tubes in the centrifuge and watch the agglutination found

3- Rhesus factor "Rh"
Is a complex antigen "D" found on the red blood cells and has its anti in the serum of the blood. 85 % are Rh + which has D in their blood Its very dangerous if persons, which are Rh negative received Rh positive it makes agglutinations, and may lead to death.

Method :
-As in the blood grouping
-Put a drop of blood + a drop of anti D
Mix together, observe the agglutination -
-If found any agglutinations, its Rh positive.

4-direct & indirect coombs test

This test is carried out to detect the presence of incomplete antibodies, which would react with double of complete antigen making a clot. And these are very serious and dangerous cases.

A- direct coombs test

Detect antibodies reactive with RBCs and conjoined Bhaotkon these objects is incomplete and not have the ability to cause coagulation alone and shows Taktherha only after the addition of serum Coombs.

This test is very important in diagnosis many cases, the most popular is "Hemolytic anemia of new born", lead poisoning, some drugs, inherited hemolytic anemia.


-Add drops of blood in a test tube and wash using saline 2-3 times( "wash" as the word means, add saline to the blood and through the filtrate 2-3 times making a bloody suspension) - add 2 drops to the washed Rbcs, and put the tube in the centifuge - examine the formation of any agglutination first with nacked eyes then using microscope. - if found it’s a positive coombs test

B- indirect coombs test:
to detect the presence of free antigens in the blood, not attached to red blood cells.

1- prepare a sample of blood group O+ and wash with saline 2-3 times 2- put drops of patient serum in a test tube, add 2 drops of washed O+ blood 3- put in a water bath for 40-60 minutes
4- after 50 minutes add "bovine serum albumin" to the tube
5- wash again with saline 3-4 times
6- add 2 drops of coombs anti human globuline,
and then put into centrifuge
7- observe the presence of agglutination
8- if found before add coombs reagent = presence of anti D
9- If found after add coombs reagent= presence of incomplete anti D 10- If not found at all= negative test.


5-cross matching
The cross matching test is very important in case of blood transfusion from donors to acceptors as the blood group and Rh should be identical to each other. So sample of blood of donor and acceptor is added to each other and checking for any formation of clotting, if found that indicates that they are not suitable for each other

At first the blood group and the Rh...
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