Blood Groups

Question 1

Approximately how many different blood group systems are there?

Answer 1

35

Question 2

What blood group systems are the most clinically significant?

Answer 2

ABO and Rh

Question 3

Whenever an A or/and B antigen is not present on the red cells the corresponding antibody is found in the plasma. True or false?

Answer 3

True

Question 4

What blood group is the universal donor?

Answer 4

O negative 
(No AB or rhesus antigens on donor RBC surface)

Question 5

What blood group is the universal acceptor?

Answer 5

AB positive

Does not have A,B or Rh antibodies in blood

Question 6

Describe blood group A

Answer 6

A antigen on RBC

Anti B antibodies in plasma

Question 7

Blood group A is compatible with what blood in an emergency?

Answer 7

A or O

Question 8

Describe blood group B

Answer 8

B antigen on surface RBC

Anti A antibodies in plasma

Question 9

Blood group B is compatible with what blood type in an emergency?

Answer 9

B or O

Question 10

Describe blood group AB

Answer 10

Has both A and B antigens on surface RBCs

Neither A nor B antibodies in plasma

Question 11

What blood group is compatible with AB in an emergency?

Answer 11

AB, A, B, O

Question 12

Describe group O

Answer 12

Neither A nor B antigens on surface of RBCs

Anti A and B antibodies in plasma

Question 13

Blood group O is compatible with what blood group in an emergency?

Answer 13

Blood group O

Question 14

Why don’t antibodies in the donor’s blood attack recipient’s RBCs?

Answer 14

Whole blood not used for routine transfusions (usually packed red cells), so plasma containing the antibodies is virtually removed.

Even if plasma transfused = minor problem as small amount of antibody present in donated plasma

Question 15

Why can ABO incompatible blood transfusion be life threatening?

Answer 15

Can cause intravascular haemolysis (destruction of red cells)
= a never event

Question 16

What can intravascular haemolysis lead to?

Answer 16

Shock
Renal failure
DIC

Question 17

What are the 5 main Rh antigens ?

Answer 17

C,c,D,E,e for which you can be either positive or negative

Question 18

What is the most important Rh antigen in clinical practice?

Answer 18

RhD

Either rhesus D positive or negative

Question 19

What percentage of the population is rhesus D positive?

Answer 19

85%

Question 20

What happens when Rhesus D positive blood is transfused into D negative patient?

Answer 20

The recipients immune system detects the D antigen on the donor red cells as a foreign substance and produces anti D antibody - not an issue for patient (cannot attack own RBCs as do not have RhD present on own RBCs)

BUT if receive another transfusion of group D positive blood, the anti D antibody in blood will attach to the D antigen on donor cells, causing agglutination and start a series of immune responses

Question 21

Describe how haemolytic disease of the newborn (HDN) can occur?

Answer 21

Rhesus D neg woman pregnant with rhesus D pos foetus and during birth comes into contact with RhD pos blood, so develops antibodies to it.

During second pregnancy with rhesus pos child, the mothers anti D antibodies cross the placenta and enter foetal circulation, where they bind to Rh D pos antigens on surface of RBCs . As a result foetal immune system destroys own RBCs = foetal anaemia

Question 22

Who should not be transfused with D (or K) positive red cells?

Answer 22

D negative females of child bearing potential (except in an emergency)

Rhesus D neg transfusion dependent patients - anti D could make it harder to find suitable blood to crossmatch