Forward and reverse grouping by Negash Alamin

Short note about forward and reverse grouping in Immunohematology

1. Title: Forward and Reverse blood grouping method
Author: Negash Alamin
Occupation: Clinical labscientist
E-mail: [email protected]
Date: August 30, 2018

2. Test: Forward and Reverse blood grouping

Sample: Anticoagulated blood

Principle: Patient’s blood components namely plasma and pellets (RBC sediments) are mixed in
five different test tubes and the blood compatibility is determined.

Materials:
1-Test tubes
2-Micropippette
3-Normal saline
4-Test tube rack
5-Anti-A, anti-B, and anti-D vials

Procedure:
1- Collect 3-5 ml of venous blood
2- Centrifuge 5000 rpm for 5 minutes and separate the plasma
3-Wash the pellet 2xs: meaning the sedimented RBC part
4- Prepare 3-5 % cell suspension i.e. 250 microliters cell plus 5 ml normal saline
Note: 3-5% of your concentrated RBC without plasma is 250 microliters of RBC concentrate
mixed with 5 ml saline.
5-Prepare 5 test tubes and label
6-Add anti-A and anti-B to 1 and 2 tubes
7-Add known A and B cell concentrates to 3 and 4
8-Add one drop anti-D to test tube 5 and 1 drop of pellet to it
9- Centrifuge all tubes for 1 minute and read results for any agglutination in any tube

3. 10. Designate the blood type of patient according to the agglutinated tubes.



Clinical significance: Forward and reverse grouping are routinely used in lab medicine to
determine patient’s blood group; differently from the slide blood grouping test. If we want to
conduct compatibility testing we use other three methods called rapid cross matching,
emergency cross matching and standard cross matching. To determine compatibility; but in
Forward and reverse grouping we determine what blood type the patient has. Whereas, in cross
matching together with IAT (indirect antiglobulin test), DAT (direct antiglobulin test), & elution
testing we specifically look for various antigens and antibodies in general.

N.B The above picture depicts reactions in ABO blood group only. It cannot indicate Lewis,
Duffy, Kidd, Lutheran or any other minor blood grouping.