IMMUNOHAEMATOLOGYABO GROUPINGPRACTICAL(1)

Nada Mohamed Ahmed ,MD, MT (ASCP)i

ABO blood grouping

Blood groups are :-Group A : red blood cells contain A antigens and

the plasma has anti-B antibodies.

Group B : B antigens are found in the red blood

cells and anti-A antibodies in the plasma.

Group AB : the red blood cells have both A and B

antigens, however there are no antibodies.

Group O : this time the plasma contains both types

of antibodies but neither type of antigen.

Methods of ABO:-

Three manual methods can be used when performing blood grouping:  - Slide method - Test tube method  - Microwell plate or microplate  method

Slide or Tile Testing 

This technique may be used for emergency ABO grouping tests or for preliminary grouping particularly in an outdoor camp, however it should always be supplemented with a cell and serum grouping using any one of the other above mentioned techniques.

Disadvantages 

- Less sensitive than the tube test  - Drying up of the reaction mixture can cause aggregation of cells, giving false positive results. - Weaker reactions are difficult to interpret. 

Procedure:- 

1. Place 1 drop of anti-A and 1 drop of anti-B reagent separately on a labeled slide .

2. Add 1 drop of blood to each drop of the typing antiserum 3. Mix the cells and reagent using a clean stick. Spread each mixture evenly on the slide over an area of 10-15 mm diameter. 

4. Tilt the slide and leave the test for 2 minutes at room temperature (22°-24°C). Then rock again and look for agglutination. 

5. Record the results. 

Forward Grouping Reagent

7

Determination of the blood group in labs

Blood groups are determined using serological tests:

• Tube Testing 

The tube technique is more sensitive than slide technique for ABO grouping. 

Advantages of tube testing 

- It allows for fairly long incubation without drying up of the tubes’ contents. - Centrifugation involved enhances the reaction allowing weaker antigens and antibodies to be detected. - Simplicity of reading and grading of results. - Clean and more hygienic. - Requires smaller volume of reagents. 

Step 1. Label test tubes.

10

Step 2: Make a 2-5% patient red cell suspension.

11

Step 3: Add reagent antisera (1 drop).

12

Step 3A: Add reagent Anti-A antisera (1 drop).

13

Step 3B: Add Anti-B reagent antisera (1 drop).

14

Step 4: Add one drop of 2-5% suspension of patient RBC to each tube.

15

Step 5: Mix and centrifuge (approximately 20 seconds).

16

Group A: Agglutination with Anti-AN0 Agglutination with Anti-B

17

Group B: Agglutination with Anti-BN0 Agglutination with Anti-A

18

Group AB: Agglutination with Anti-A and Anti-B

19

Group O:No Agglutination with Anti-A or Anti-B

20

Write about new technique used in ABO grouping