Blood Transfusions

Question 1

What are reasons for transfusing blood?

Answer 1

• bleeding
• failure of production

Question 2

What determines blood groups?

Answer 2

• arise from antigens
• red cell antigens expressed on cells surface
• can provoke antibodies
• Type A- A glycoproteins
• Type B- B glycoproteins
• Type AB- A + B glycoproteins
• Type O- no glycoproteins

Question 3

Which blood donors groups are compatible with which blood recipient groups?

Answer 3

Question 4

What is RhD blood groups?

Answer 4

• RhD positive- RhD antigen/Rhesus positive
• RhD negative- no Rhd antigen/Rhesus negative

Question 5

What happens if an RhD negative individual is exposed to RhD+ blood cells?

Answer 5

• pregnancy or transfusion
• make anti-D
• anti-D cause transfusion reactions, haemolytic disease in newborns

Question 6

What are blood donors screened for?

Answer 6

• sex, age, travel, tattoos
• ABO + Rh blood grou
• Hep B/C/E, HIV, syphilis
• HTLV1, malaria, West Nile virus, Zika virus

Question 7

What are indications for red cell transfusions?

Answer 7

• severe acute anaemia, which may cause organ damage
• improve quality of life in uncorrectable anaemia
• prepare for surgery or speed recovery
• reverse damage caused by patients own cells
• sickle cell disease

Question 8

How are red blood cells stored and transfused?

Answer 8

• stored at 4˚C
• transfuse over 2-4 hrs
• 1 unit increments ~ 5g/L

Question 9

What are indications for platelets?

Answer 9

• massive haemorrhage
• bone marrow failure
• prophylaxis for surgery
• cardiopulmonary bypass
• use only if bleeding

Question 10

How are platelets stored and transfused?

Answer 10

• stored at ~22˚C
• shelf life 7 days
• transfused over 20-30 mins

Question 11

What are the components of plasma?

Answer 11

• fresh frozen plasma (FFP)
• 1 unit from 1 unit of blood
• stored frozen, 30 mins to thaw
• massive haemorrhage, DIC with bleeding, prophylactic
• cryoprecipitate
• 1-2 pool if fibrinogen < 1.0g/dl
• stored frozen, 20 mins to thaw

Question 12

What is the direct and indirect Coombs test?

Answer 12

• direct- detects antibodies on surface of RBC
• autoimmune haemolytic anaemia
• passive anti-D
• haemolytic transfusion reactions
• indirect- dectects free antibodies in blood
• cross matching

Question 13

What is haemolytic disease of the newborn (HDN)?

Answer 13

• erythroblasosis fetalis
• baby’s RBCs brake down at a fast rate

Question 14

What causes haemolytic disease of the newborn (HDN)?

Answer 14

• RhD -ve mother and +ve baby (most immunogenic)
• c, K
• other Rh antigens, Jka, ABO
• +ve DAT at birth, anaemia, jaundice

Question 15

What is the prevention and treatment for haemolytic disease of the newborn (HDN)?

Answer 15

• prevention using prophylactic anti-D
• sensitising events
• routine at 28/40
• treatment by careful monitoring
• antibody titres
• Doppler US
• intrauterine transfusions
• neonatal alloimmune thrombocytopenia (NAIT)

Question 16

What are cellular therapies?

Answer 16

• leucapheresis
• bone marrow harvests
• donor lymphocyte infusions
• ‘other banks’
• bone, milk, tendons, heart valves, faecal
• islet cells, mesenchymal stem cells
• gene therapies