Question

1. State two reasons why a patient could have a negative alloantibody screen, but one unit of incompatible blood.

2. Discuss the selection of blood for transfusion for each of the following scenarios:

- routine situation

- emergency situation

- when blood group specific blood is not available

- when Rh type specific blood is not available

Answer 1

1.

- Antibody screening red cells are group O and the antibodies are anti-A or anti-B.

- A low to moderate frequency antigen is present on the cross matched red cells , but not on the antibody screening red cells. Example :- Wr a, Kp a, Js a, C w, Di a, Go w, Sc2, Mi a, Lu a, Co b, and Yt b.

2.

* ROUTINE SITUATION

- Blood should be obtained from carefully selected regular voluntary non- remunerated donors.

- Before blood transfusion therapy, patient should have extended red cell antigen typing that includes atleast C, c , D , E, e and kell inorder to help identify and charecteric antibodies in case of later immunisation.

- If a patient is already transfused, antigen typing can be performed using molecular rather than serologic testing.

- Serologic testing

- Transfusion of blood from first degree relatives should be avoided , because if the risk of developing antibodies that might adversely affect outcome of a later stem cell transplant and the risk of transfusion associated graft versus host disease.

*EMERGENCY SITUATION

- Recieve bloodband plasma of same ABO and RhD group.

- O RhD negative red cells are issued in emergency situation where Life saving Transfusion is required prior to completion of a crossmatch.

- We hypothesized that patients given uncrossmatched blood may develop allo antibodies , placing them at risk for hemolytic Transfusion reaction.

WHEN BLOOD GROUP SPECIFIC BLOOD IS NOT AVAILABLE

When ABO specific blood is not available , it is important to use RBCs that are still compatible when the recipient's serum , that is crossmatch compatible. Donor RBCs must not contain A or B antigen that react with the anti A / anti B present in the recepients serum.

WHEN Rh TYPE SPECIFIC BLOOD IS NOT AVAILABLE

O RhD negative red cells are issued when Rh type specific blood is not available.

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