blood groups and transfusions

Question 1

where are blood groups found?

Answer 1

on the surface of RBCs

Question 2

what is the ABO blood group made of?

Answer 2

sugar residues

Question 3

what is he Rh blood group made of?

Answer 3

proteins

Question 4

what determines the blood group?

Answer 4

genes

Question 5

what are antibodies

Answer 5

immunoglobulins in plasma which react specifically with their antigen

Question 6

what are autoantibodies?

Answer 6

react with antigens present on person’s own RBCs

Question 7

what are alloantibodies? what types are there?

Answer 7

produced by the person against antigens not present on their own RBCs

• Naturally occurring (exposure to environment)
• Immune (contact with antigen)

Question 8

at what temperature does IgM bind?

Answer 8

room emp

Question 9

what does IgM do?

Answer 9

activates complement

Question 10

name the ABO blood groups and their antibodies

Answer 10

A (has anti-B in plasma)
B (has anti-A in plasma)
O (has anti-A and anti-B in plasma)
AB (has no ABO antibody in plasma)

Question 11

what is the ABO phenotype?

Answer 11

antigens detectable on RBC membrane

Question 12

what is the ABO genotype?

Answer 12

antigens encoded in DNA (one copy from each parent)

Question 13

what are the possible genotypes for blood group A?

Answer 13

AA, AO

Question 14

what are the possible genotypes for blood group B?

Answer 14

BB, BO

Question 15

what are the possible genotypes for blood group AB?

Answer 15

AB (codominant)

Question 16

what are the possible genotypes for blood group O?

Answer 16

OO

Question 17

how many pairs of proteins are there in the Rh blood group system and how are they inherited?

Answer 17

3 pairs of proteins, inherited as triplet

Question 18

what are the proteins of the Rh blood group?

Answer 18

• D or no D (d)
• C or c
• E or e

Question 19

what type of antibodies are formed in the Rh blood group and how can they form?

Answer 19

immune only

form on exposure; transfusion, pregnacy and transplantation

Question 20

how can the Rh phenotype be determined?

Answer 20

serologically

Question 21

what antibodies will agglutinate CcDE?

Answer 21

agglutinate with anti-C, anti-c, anti-D, anti-E but not anti-e

Question 22

what antibodies will aggluinate cdE?

Answer 22

anti-c
anti-E
there’s no anti-d

Question 23

explain how a mother can damage the fetal RBCs?

Answer 23

Rh+ father and Rh- mother carrying her first Rh+ fetus
Rh antigens from the developing fetus can enter the mother’s blood during delivery
In response to the fetal Rh antigens, the mother will make anti-Rh antibodies
If the woman becomes pregnant again with another Rh+ fetus then her anti-Rh antibodies will cross the placenta and damage the fetal RBCs

Question 24

what are the consequences of having a Rh- mother and her second Rh+ fetus?

Answer 24

Fetal anaemia – can be fatal

Neonatal jaundice – can cause brain damage

Question 25

how is a Rh- mother with a Rh+ baby treated?

Answer 25

- Prophylaxis after a sensitising event during pregnancy Prophylactic anti-D Ig all D negative mothers in third trimester - Postnatally if baby D positive - Free fetal DNA testing for RHD typing of of foetus from maternal sample now available to help targeted Anti D prophylaxis

Question 26

name methods of good clinical blood transfusion practice?

Answer 26

``` Monitoring adverse reactions Patient identification Sample labelling Lab testing Selection of component Transfer to clinical area Appropriate use ```

Question 27

how should RBCs be stored?

Answer 27

4 degC | shelf life of 35 days

Question 28

name some indications for transfusions and give examples

Answer 28

Blood loss - Surgery, Trauma, Obstetric haemorrhage Bone marrow failure - Leukaemia, cancer, drugs Haemolysis - Malaria, sepsis, immune, haemolytic disease of newborn Inherited haemoglobin disorders - Thalassaemia, Sickle cell anaemia (Anaemia due to Iron, B12 or folate deficiency) - Avoid transfusion– give haematinic replacement therapy instead.

Question 29

what should you do after you take blood from a patient?

Answer 29

confirm identification by speaking to them (use wrist-band if unconscious) label tube after filling with blood with full name, date of birth and hospital record number ensure that no discrepancy between details on bottle and form sign both form and tube to confirm

Question 30

how does an antibody screen work?

Answer 30

- indirect antigloblin test is used to detect IgG (alloantibodies formed after previous pregnancy or transfusion) - Patient’s plasma mixed with group O cells expressing ALL the common blood group antigens – e.g. Rh C c D E e, and many others - If an antibody is present it will bind to the antigen on the ‘detector’ red cells and screen will be positive

Question 31

explain how an indirect antiglobulin test occurs?

Answer 31

``` Patient’s serum with IgG Incubation with reagent RBCs Binding of any IgG to reagent RBCs Incubation with antibodies to human Ig Agglutination (+ve indirect Coombs test) ```

Question 32

how does serological cross match work?

Answer 32

mix donor red cells and patient serum to check compatible Must do if antibody screen positive or not eligible for electronic ‘crossmatch’ If red cell antibodies then select units negative for those antigens and serologically crossmatch to check compatibility

Question 33

how do you carry out a blood transfusion?

Answer 33

``` Positively identify patient by name, DOB and hospital number Before transfusing must confirm Identity of patient Blood group of patient Blood group of the unit of blood Start transfusion Monitor closely (especially initially) Pulse, blood pressure and temperature ```

Question 34

what are the signs and symptoms of a transfusion reaction?

Answer 34

Symptoms: restless, flushing, anxiety, abdominal pain, nausea and diarrhoea, abdominal pain, pain at venepuncture site Signs: Fever, hypotension, haemoglobinguria

Question 35

how do you treat someone who has had a possible transfusion reaction?

Answer 35

STOP TRANSFUSION | Maintain venous access with saline, commence resuscitation

Question 36

how do you investigate a transfusion reaction?

Answer 36

Take samples for full blood count, renal and liver function tests blood cultures, coagulation screen, Repeat compatibility testing pre and post transfusion plasma Direct Antiglobulin Test assessment of urine for haemoglobin High dependency management – renal support, DIC

Question 37

when does a delayed haemolytic transfusion reaction occur and how does it present?

Answer 37

7 to 10 days post transfusion Failure of haemoglobin to rise Jaundice

Question 38

what regulatory bodies do you report transfusion adverse effects to?

Answer 38

SHOT (Serious Hazards of Transfusion) - Collects information on adverse events and feedbacks to hospitals to improve transfusion overall safety Blood Safety and Quality Regulations require mandatory reporting to: MHRA (Medicines and Healthcare products Regulatory Agency) SABRE (Serious Adverse Blood Reactions and Events)