Blood Types and Safe Prescription

Question 1

Describe the ABO and Rhesus bloos grouping systems.

Answer 1

• Presence of antigens on the surface of red blood cells determines blood type.
• The golden rule of transfusion is that patients should not be given blood containing antigens which their own blood does not have. The body will identify new antigens as foreign and develop antibodies to attack these.

Question 2

Which of the blood types is the universal donor?

Answer 2

• O
• Because it does not have any antigens on its surface and therefore by giving it to someone else they would not be receiving blood with surface antigens they do not recognise.

Question 3

Can a rhesus D negative patient receive blood from a rhesus positive donor? Defend.

Answer 3

• No​
• The opposite, however, is fine. A Rh-D + patient can reveive blood from a Rh-D- donor.

Question 4

What are the rules of dominance for the ABO system?

Answer 4

• A and B are both dominant over O (i.e. O is recessive).
• A and B are codominant.

Question 5

If one of your parents is blood type A and the other is type B, which of the following blood types would you likely be?

• A
• B
• AB
• O

Answer 5

• Any of the above.
• Since you could inherit A or O alleles from one parent and B or O alleles from the other, you could be any of the 4 ABO types.

Question 6

What are the different types of transfusion reactions?

Answer 6

• Acute haemolytic reactions
• Delayed haemolytic reactions
• Urticaria or anaphylaxis
• Febrile reactions

Question 7

Describe an acute haemolytic transfusion reaction.

Answer 7

• Immediate reaction.
• Patient gets fever, shivers, back pain, free Hb in urine.
• Usually from pre-existing antibodies (someone from O getting A blood).

Question 8

Describe an delayed haemolytic transfusion reaction.

Answer 8

• New antibodies following transfusions.
• 1-2 weeks after transfusion becoming anaemic and a bit jaundiced because the patient has made antibodies against antigens they do not normally carry themselves.

Question 9

Describe urticaria and anaphylaxis transfusion reactions.

Answer 9

• Urticaria is the mild end of spectrum - treat with piritin or hydrocortisone.
• Due to the presence of drugs or plasma proteins in the donor blood.

Question 10

Describe febrile transfusion reactions.

Answer 10

• Temperature goes up during transfusion - thought to be due to patient picking up HLA types in the blood which they do not carry themselves.
• All blood now is leukocyte-depleted as a way of preventing CJD being transmitted from blood.
• It means that patients get far fewer HLA type reactions because of the white cell depletion.

Question 11

Describe why and how the process of cross matching blood for patients is carried out.

Answer 11

• Donor blood is checked for ABO and RhD and other antigens. Also, microbiology screening for HIV / HCV / HBV etc.
• Recipient’s blood is checked for ABO and RhD and the plasma is screened for antibodies against a panel of red cell antigens.
• To account for possible incompatibilities outside ABO and Rh, an additional test is made before transfusion.
• A blood sample from the patient is mixed with a sample of donor blood and the mixture is examined for agglutination (clumps). No clumps = compatible match.

Question 12

Discuss the risks associated with blood transfusion.

Answer 12

• Major risk is transfusion reaction.
• Pulmonary complications – patient can get circulatory overload.
  
  • Their volume increases and they get pulmonary oedema.
• Transfusion associated dyspnoea.
• Transfusion-associated lung injury.