Transfusion

Question 1

What criteria must patients meet in order to be allowed to given blood?

Answer 1

Healthy donors req’d
=> Hb level 135 for men and 125 for women
=> Minimum weight 50kg
To avoid donors becoming anaemic after giving blood

Question 2

How is blood processed centrally before being used for transfusion?

Answer 2

• centrifuged to separate into component parts
  (red cells, FFP and platelets)
• These then undergo HIV/Hep/syphilis testing

Question 3

How long do red cells, FFP and platelets last for?

Answer 3

• Red cells for 35 days in fridge
• FFP for 2-3 years in freezer
• platelets for 7 days at room temp

Question 4

What other blood products are available from the transfusion lab?

Answer 4

• Anti-D
• Prothrombin complex concentrate (help pts clot)
• IV Immunoglobulin
• human albumin

Question 5

What is meant by the ABO blood grouping system?

Answer 5

• Genes on chromosome 9 code for transferases

- These modify ‘H substance’ on red cell membrane

Question 6

What are the most common blood groups in the UK?

Answer 6

O and A

Question 7

What antigens and antibodies are found on Blood group A?

Answer 7

A antigen and Anti-B antibodies

Question 8

What antigens and antibodies are found in blood group B?

Answer 8

B antigens and Anti-A antibodies

Question 9

What antigens and antibodies are found in blood group AB?

Answer 9

A and B antigens, no antibodies

Question 10

What antigens and antibodies are found in blood group O?

Answer 10

no antigens and anti-A and anti-B antibodies

Question 11

Blood group O has an autosomal recessive inheritance pattern. TRUE/FALSE?

Answer 11

TRUE
A and B are dominant over O
=> must be OO alleles to have blood group O

Question 12

What is the difference between RhD positive and negative?

Answer 12

RhD+ has D antigens on RBCs and NO D antibodies

RhD- has no D antigens but Anti-D antibodies

Question 13

What blood group can be given to any patient, regardless of their blood group?

Answer 13

O negative

Question 14

What percentage of the UK population are RhD positive?

Answer 14

85%

Question 15

Is RhD negative an autosomal dominant or recessive trait?

Answer 15

Recessive
RhD+ is dominant
=> pt must be “dd” to be RhD negative

Question 16

Can RhD cause a transfusion reaction?

Answer 16

Yes
- can cause reaction and haemolytic disease of foetus and newborn

=> RhD negative patients should only be given RhD negative blood

Question 17

When may antigens/ antibodies other than the ABO and Rhesus systems cause transfusion reactions?

Answer 17

If patient exposed to new antigen (e.g. through pregnancy or previous transfusion) then repeat exposure may result in transfusion reaction

Question 18

How are patients ABO grouped before transfusion of blood?

Answer 18

• Identify antigens present on red cell using Antisera

OR identify antibodies with Reagent red cells

Agglutination will tell you what blood group is
=> can also be done with other antibody types to prevent an unknown transfusion reaction

Question 19

What is meant by crossmatching blood to check it is suitable for transfusion?

Answer 19

• check if donor cells are incompatible with patient plasma.
• If NO agglutination- cells can be issued for transfusion.

Question 20

What are the main indications for a blood transfusion?

Answer 20

• Symptomatic anaemia Hb<70g/L
• Major bleeding

remember to consider transfusion alternative

Question 21

How many units of blood should be transfused before reassessing a patient?

Answer 21

single unit of red cells, then reassess patient

Question 22

Why would a patient need a platelet transfusion?

Answer 22

• Prophylaxis in bone marrow failure/ Treatment of bleeding in thrombocytopenic patient
• Prophylaxis prior to surgery/ procedure in thrombocytopenic patient

Question 23

Why would patients need a fresh frozen plasma transfusion?

Answer 23

• Treatment of bleeding in patient with coagulopathy (PT ratio >1.5)
• Prophylaxis prior to surgery
• Tx of haemorrhage or trauma

Question 24

How should patients be monitored during transfusion?

Answer 24

Before blood is commenced

Obs at 15 mins then 60 mins after completion