Blood transfusion

Question 1

When do you use blood tranfusions?

Answer 1

If there is no other possbility

mainly in emergency situations

• trauma + massive bleedings
• very severe anaemia
• clotting disorders etc.

Question 2

What does the A gene in blood groups code for?

Answer 2

It codes for an enzyme adding galactosamine to fructose stem on cells

–> forms the A antigen

Question 3

Which antigens and antibodies does a person with blood group A have?

Answer 3

A= A antigens and

Anti-B- antibodies –> can’t get blood that has B antigens (i.e. B+AB)

Question 4

Which Antigens and Antibodies does someone with Blood group B has?

Answer 4

B

• B-Antigen
• Anti-A-antibody
• –> can’t get blood with A antigen (i.e. A+AB)

Question 5

Which Antigens and Antibodies does someone with blood group AB have?

Answer 5

AB

• AB antigens
• no anti-antibodies
• –> can recieve any blood donation

Question 6

Which antigens and antibodies does someone with blood group 0 have?

Answer 6

They have

• no antigens
• Anti -A- and Anti B antigens
• –> can give blood to anyone

Question 7

Why don’t the Anti- A and Anti-B antibodies in the plasma not affect the blood donation (0) given to patients with groups A or B?

Answer 7

Normally no full blood transfustion

• only packed red cells and no plasma

Question 8

What happens if you would give a blood transfusion of group B to someone with group A?

Answer 8

IgM anti-B antibodies would bind to blood cells by group B and set of a cytokine strom–>

• lysis of erythrocytes
• aggulation seen (IgM mediated)

Question 9

Explain the process of blood group testing and matching blood

Answer 9

You need

1. patients sample
2. test with known anti-A/anti-B antibodies

–> Combine and look for reaction (if aggulation reaction –> not suitable for donation)

If necessary:

• X match with donor blood + recipient

Question 10

Explain the possible genotype for a RhD + and -ve person

Answer 10

+ ve: Dd or DD

-ve dd

–> recessive gene

Question 11

Explain the possible genotype of someone having blood group A+B

Answer 11

• A= AA or AO
• B= BB or BO

Question 12

What happens to RhD -ve people who are exposed to the RhD antigen?

Answer 12

They don’t have the RhD antibody from birth but can develop them furter in life–> can lead to problems in

• another blood transfusion that is +ve (where you would react then)
• in pregnancy with a -ve mother and a +ve foetus –> antigens would destroy the foetus blood cells

Question 13

What happens when you transfuse a RhD -ve person who has developed Anti-D antigens a RhD +ve transfusion?

Answer 13

otherwise his anti-D would react with RhD posblood - causes delayed haemolytic transfusion reaction - anaemia; high bilirubin; jaundice etc

Reaction within 5-10 days

Question 14

What is the significance of other antigens present on red blood cells other than A, B and RhD?

Answer 14

Only 8% of people develop antibodies against antigens they don’t have –> normally not matched for

If once antibodies have developed: must use corresponding antigen negative blood otherwise:

risk of delayed haemolytic reaction (can be severe)

Question 15

Which tests are required to do before a transfusion?

Answer 15

ABO and RhD group, must do an ‘antibody screen’ of their plasma

–> for all the other possible antigens in blood/ on blood cells

Question 16

In which 3 components is a standart blood sample normally devided?

Answer 16

Normally in

• Red cell component
• Platelets
• Plasma

Question 17

When do you give red cells in a blood transfusion?

Answer 17

e..g in patients with trauma, hugh blood loss to restore oxygen carring capacity

Question 18

What does a FFP contain?

Who would recieve it?

Answer 18

FFP= Fresh Frozen plasma (frozen and thawed before use)

• contains coagulation factors

Given to people with reduced blood coagulation (slowed PT+ APTH test)

reversal of warfarin for urgent surgery

Same blood group needed but no x-maching necessary

Question 19

What is cryoprecipitate?

Who needs it?

Answer 19

Part of plasma high in Fibrinogen and Facotr VIII

Given to patients with

• massive bleeding and fibrinogen very low
• Rarely hypofibrinogenaemia

Question 20

What are the characteristics of a platelet donation?

Who recieves it?

Answer 20

Shelf life of only 5 days with agitation

• no x match required but choose same blood group (as otherwise lifespan of platelets shortened)
• RhD sensitisation possible (because of contamination with red cells)

Given to patients with

• thrombocytopaenia
• Mainly in cancer/bone marrow failure
• also in massive bleeding of DIC
• reversing effects of anti-platelet drugs

Question 21

Which blood transfusion products are usually obtained via fractionated prodcuts?

Answer 21

1. Single clotting factors
   
   • VIII, IX in haemophilia
   • Factor VIII in VWD (because is VWB factor is low, VIII is also low (VWB stabelises factor VIII)
2. lImmunoglobulins
3. Albumin

Question 22

Explain the transfusion of Immunoglobulins

Answer 22

Used for:

• IM: Specific - tetanus; anti-D; rabies
• IM: Normal globulin - broad mix in population (eg: HAV)
• IVIg – pre-op in patients with ITP or AIHA

Question 23

How are blood donors tested?

What are the criteria?

Answer 23

Blood donors within high risk groups/risk behaviours are excluded

Blood is tested for infections (no 100% certainty):

• Hepatitis B - HBsAg, PCR
• Hepatitis C - anti-HCV, PCR
• HIV - anti-HIV, PCR
• HTLV - anti HTLV
• Syphilis - TPHA (spirochete)
• Hepatitis E - PCR
• Some also tested for CMV (virus)

Questionnaire: e.g. malaria (exclude when recent travelling etc.)

vCreutzfeldt-Jacob disease also can be transmitted but very very rare

Question 24

How are platelet donations stored and what is their shelf life?

Answer 24

Stored at 22° (Room temperature and constantly agitated)

Shelf life: 5 days

(increased risk of infection due to warm storing temp)

Question 25

What is the storage and shelf life of FFP?

Answer 25

Fresh Frozen Plasma

(Same storage for Cryorecipitate)

• collected (300ml) and frozen within 6h
• Stored at -30°
• Shelf Life: 2 years