Blood groups and transfusions

Question 1

What is the difference between autoantibodies and alloantibodies?

Answer 1

Autoantibodies: react with antigens present on person’s own red blood cells

Alloantibodies: produced by the person against foreign antigens

Question 2

Describe the different blood groups.

Answer 2

Group a: anti-b antibodies in plasma
- will be agglutinated by anti-a antibodies

Group B: has anti-a antibodies in plasma
- will be agglutinated by anti-b antibodies

Group O: has anti-a and anti-b antibodies in plasma
- will not be agglutinated by anti-a or anti-b antibodies

Group AB: has no ABO antibody in plasma
- will be agglutinated by anti-a and anti-b

Question 3

What are the 5 main Rhesus antigens, and what are the most frequent phenotypes?

Answer 3

Antigens: C, c, D, E, e
Phenotypes:
- Dce
- cde
- DCe
- dCe
- DcE
- dcE
- DCE
- dCE

Question 4

Why is Rhesus antigen D the most important?

Answer 4

Antigen D is immunogenic and provokes an immune response

Question 5

In an emergency situation where a blood transfusion is required, but the blood type of the patient is unknown what should be done?

Answer 5

Give O-ve blood (but it is limited and precious)

• Can give O+ve blood to males requiring a massive transfusion (will not mount an immune response immediately)
• DO NOT give a woman of child-bearing age O+ve blood

Question 6

What is haemolytic disease of the newborn? How can it be prevented?

Answer 6

• Rh -ve mother and Rh +ve baby –> mother mounts an immune response to the Rh D antigen –> this damaged foetal RBCs
• can causes foetal anaemia (can be fatal) and can cause foetal jaundice (can cause brain damage)

Prevented via prophylactic treatment –> give D-negative mothers anti-DIg in the third trimester

Question 7

At what temperature are RBCs stored at? What is their shelf-life?

Answer 7

4 degrees celsius
35 days (shelf-life)

Question 8

What are the indications for blood transfusion?

Answer 8

1. blood loss (surgery, trauma, obstetric haemorrhage)
2. bone marrow failure (leukaemia, cancer, drugs)
3. haemolysis (malaria, sepsis, immune, haemolytic disease of newborn)
4. inherited haemoglobin disorders (thalassaemia, sickle cell)

Question 9

What is a haematinic?

Answer 9

Nutrient required for the formation of RBCs (iron, B12, folate)

Question 10

When are haematinics given?

Answer 10

Act as a replacement therapy in iron/B12/folate deficiency-related anaemia

Question 11

What complications are associated with transfusions?

Answer 11

Non infectious:

1. Immune
   - acute haemolytic transfusion reaction/incompatible transfusion
   - delayed haemolytic transfusion reaction
   - febrile non haemolytic
   - allergic
   - post-transfusion purpura
   - transfusion related to acute lung injury
2. Non-immune
   - fluid overload
   - iron overload

Infectious:

• viral
• bacterial
• syphilis
• parasites
• prions

Question 12

What are the S+S of a transfusion reaction?

Answer 12

Symptoms:

• restless
• flushing
• anxiety
• abdominal pain
• nausea
• diarrhoea
• pain at venipuncture site

Signs:

• fever
• hypotension
• haemoglobinuria

Question 13

How should transfusion reaction be managed?

Answer 13

Stop the transfusion if S+S are present

Maintain venous access with saline and commence resuscitation

Question 14

What is delayed haemolytic transfusion reaction? What type of antibody is involved?

Answer 14

Delayed reaction that occurs 7-10 days post-transfusion haemoglobin fails to increase
can also result in jaundice
due to red cells antibodies (IgG)
Direct antiglobulin test will be positive