Blood groups and transfusion

Question 1

Blood types

Answer 1

A
B
AB
O

Question 2

ABO typing

Answer 2

Discovered by Karl Landsteiner.
ABO system - potently antigenic - antibodies occur naturally.
We will have antibodies for other blood types naturally.
ABO antigens inherited in mendelian pattern - gene on Chr 9 - codes for an enzyme rather than the sugar, another gene codes for the sugar base of the ABO antigen.

Question 3

ABO antigen

Answer 3

Have H antigen - each have a different sugar attached - O has no sugar attached.

Question 3

ABO antibodies

Answer 3

IgM - for A and B
IgG
Created after 3 months of birth - peak at 5-10 years.
Active at 37 degrees.
Everyone has them regardless of exposure.

Question 4

Universal donor and recipient

Answer 4

Universal donor - O.
Universal recipient - AB.

Question 5

Rhesus antigens

Answer 5

2 genes, chromosome 1.
RHD - codes for Rh D.
RHCE - codes for Rh C and Rh E.
Highly immunogenic.
Can cause haemolytic transfusion reactions and the haemolytic disease of the fetus and newborn.

Question 6

Haemolytic disease of the fetus/newborn

Answer 6

Common cause = Rh D.
Develop anti-Rh antibodies.
Severe fetal anaemia.
Hydrops fetalis.
Mother forms Rh D antibodies when blood mixes, second baby if Rh D positive - blood attacked.
Prevented by detecting mothers risk, maternal free DNA and anti D prophylaxis.

Question 7

ABO and Rh D grouping

Answer 7

Add RBCs and anti-A/B/D reagent.

Question 8

Cross-matching blood

Answer 8

Units of blood come from
- exact match
- ‘compatible’ blood

Question 9

Indirect Antiglobulin Test

Answer 9

Blood grouping for ABO and Rhesus D.
Detects antibodies in patient’s serum.

Question 10

Direct Antiglobulin Test

Answer 10

Detects antibodies on patient’s erythrocytes.
Used for:
- autoimmune haemolysis
- transfusion reaction
- haemolysis due to fetal/maternal group incompatibility

Question 11

Blood donor requirements

Answer 11

17-65 year olds.
Questionnaire about lifestyle.
Weight 50-158 kg.
Test for hep B, HIV, HTLV, syphilis ect.
Travel, tattoos or lifestyle - temporary exclusion.
Certain diseases, receives blood/transplants since 1980, notified at risk of vCJD - permanent exclusion.

Question 12

Blood donor - what can you donate?

Answer 12

Whole blood apheresis -
blood removed and externally separated.
Or just blood in closed bag system bags.
Centrifuged to pack red cells, buffy coat and plasma.
Plasma only kept from males.
Plasma frozen (FFP) or processed to cryoprecipitate.
Red cells passed through leucodepletion filter and suspended in additive.
Buffy coats pooled with matching ABO and D type - then leucodepleted to make platelets.

Question 13

Product - red cells

Answer 13

Stored at 4 degrees - 35 days.
Severe anaemia.
Haemoglobin - <70 g/L OR <80 g/L with symptoms.

Question 14

Product - platelets

Answer 14

Most units pooled from 4 donations.
Some single-donor apheresis units.
Stored at 22 degrees with agitation - 7 days.
Bleeding and thrombocytopaenia.
Transfusion threshold (NICE):
<10 x 10^9 - if asymptomatic and not bleeding.
<30 x 10^9 - if minor bleeding.
<50 x 10^9 - significant bleeding.
<100x 10^9 - if critical site bleeding (brain, eye)

Question 15

Products - FFP

Answer 15

From whole donations or apheresis.
Bleeding or multiple clotting factor deficiencies.

Question 16

Products - cyroprecipitate

Answer 16

From thawing FFP to 4 degrees and skimming off fibrinogen rich layer.
Used in DIC with bleeding.
Therapeutic dose - 2 packs - each from 5 donations.

Question 17

Products - immunoglobulin

Answer 17

From large pools of donor plasma.
Normal IVIg - has Ab to viruses common in population - used to treat immune conditions.
Specific IVIg - from selected patients, known high AB levels to particular conditions - Anti D immunoglobulin used in pregnancy.

Question 18

Products - granulocytes

Answer 18

Very rarely used.
Effectiveness controversial.
Life threatening bacterial infections.
Must be irradiated to kill T cells.

Question 19

Products - factor concentrates

Answer 19

Single factor - Factor VIII for severe haemophilia A, fibrinogen concentrate.
Prothrombin complex concentrate - multiple factors, rapid reversal of warfarin.

Question 20

Safe delivery

Answer 20

Patient identification.
2 sample rule.
Hand written patient details.
Blood selected and serologically cross matched.
Mistakes - identification error, too much blood transfused.

Question 21

Avoiding transfusion

Answer 21

Optimise patients with planned surgical procedures.
Use of EPO-stimulating drugs - in renal failure and cancer.
Intraoperative cell salvage.
IV iron for severe iron deficiency.

Question 22

Safety of blood

Answer 22

Very safe,
Highly regulated.

Question 23

Haemolytic reactions

Answer 23

ABO incompatibility - cytokine release, DIC, acute renal failure, can be fatal.
Treatment - stop transfusion, fluid resuscitate.
Can be acute or delayed.
Must be reported to SHOT.

Question 24

Bacterial contamination

Answer 24

Most common with platelets - very rare.
Symptoms very soon after - fever, shock, hypotension.
Unit may be abnormal in colour.

Question 25

Transfusion-related injury

Answer 25

AB in donor blood reacts with pulmonary epithelium/neutrophils.
Inflammation causes plasma to leak into alveoli.
Symptoms - DOB, cough, hypotension, fever.

Question 26

Transfusion-associates circulatory overload

Answer 26

Acute/worsening pulmonary oedema within hours of transfusion.
Older patients more at risk.
Symptoms - respiratory distress, raised BP.
Careful assessment of transfusion need and limiting amount can help avoid.