Blood Transfusion- ABO, rhesus + testing

Question 1

minimum requirements for men + women donating blood?

Answer 1

Hb- Men 135 g/L
Hb- Women 125 g/L and weigh at least 50kg

Question 2

what is done as blood donor safety for transfusions?

Answer 2

-Donor selection questionnaire
-Contact details taken incase they become ill post donation

Question 3

what diseases are tested for in blood donated?

Answer 3

-Hep B, C + E
-HIV
-HTLV (human T lymphocytic virus)
-Syphillis

Question 4

how are red cells stored?

Answer 4

at 4 degrees for 35 days

Question 5

how is FFP stored

Answer 5

-30 degrees for 3 years

Question 6

how are platelets stored?

Answer 6

22 degrees for 7 days with agitation (continously oxygenated)

Question 7

what are some products available from transfusion lab from blood donation

Answer 7

Blood components – red cells, FFP, platelets, cryoprecipitate

Blood products – anti-D immunoglobulin, prothrombin complex concentrate

Blood products from pharmacy – IV immunoglobulin, human albumin, specific Ig

Question 8

how is a blood group determined?

Answer 8

• Membrane of red cells contains may different antigens
• Which antigens will be expressed is determined by which blood group antigen genes we inherit from our parents

Question 9

where is the ABO gene located?

Answer 9

chromosome 9

Question 10

what do A and B genes code for?

Answer 10

A and B genes code for transferases which modify precursor called H substance on red cell membrane

Question 11

what is most dominant: A, B or O?

Answer 11

A and B are dominant over O
-o is silent

But A and B are co dominant

Question 12

genotype of group O blood

Answer 12

OO

Question 13

genotype of group A blood

Answer 13

AA or AO

Question 14

genotype of group B blood

Answer 14

BB or BO

Question 15

genotype of group AB blood

Answer 15

AB

Question 16

what is Landsteiners law?

Answer 16

when an individuals lacks the A or B antigen, the corresponding antibody is produced in they plasma

(so naturally occurring antibodies cause haemolysis of red cells expressing the specific antigen)

Question 17

what blood group produces no antibodies?

Answer 17

Blood group AB

Question 18

what blood type can someone with Group A blood receive?

Answer 18

Group A blood type expresses B antibodies

Can receive blood from:
-Group A
-Group O

(because group O and A wont be attacked by group B antibodies)

Question 19

what blood type can someone with Group A blood give to?

Answer 19

-Group AB (as they do not have any antibodies)
-Group A

Question 20

what blood group produces both A and B antibodies?

Answer 20

O

Question 21

what blood groups can someone with group B blood receive from?

Answer 21

-Group O
-Group B

As group B express A antibodies (so cannot receive from A or AB)

Question 22

who can someone with group B blood donate to?

Answer 22

-Group B
-Group AB

As B and AB do not express group B antibodies

O expresses AB antibodies
A expresses B antibodies

Question 23

who can someone with group AB blood receive blood from?

Answer 23

-Group O
-Group A
-Group B
-Group AB

because do not produce antibodies for any blood type

Question 24

who can someone with group AB blood donate to?

Answer 24

-Only group AB

Because:
-Group A express antibodies for group B
-Group B express antibodies for group A
-Group O express A and B antibodies

Question 25

is Rhd positive or negative more common?

Answer 25

Rhd positive (85% population)

Question 26

what are the RhD alleles and how are they inherited?

Answer 26

2 alleles D and and d
-inherit one from each parent
-d is silent

Question 27

genotype of RhD + and RhD-?

Answer 27

RhD+ is DD or dD
RhD- is dd

Question 28

what can occur if there is an anti-D antibody reacting with RhD +

Answer 28

can cause transfusion reactions and haemolyic disease of the fetus + newborn

Question 29

what type of RhD blood should RhD negative people receive?

Answer 29

RhD- blood to RhD- people

Question 30

what regeant is used to identify ABO and RhD ANTIGENS on red cells?

Answer 30

Antisera (regeant with known antibody specificity to identify antigents on red cells):
-anti A antisera
-anti B antisera
-anti D antisera

Question 31

what is used to test red cells for specific ANTIBODIES in plasma?

Answer 31

Regeant red cells
-red cells with known antigen specificity to identify antibodies in plasma

Question 32

Explain how antisera works and agglutination

Answer 32

Antisera contains known antibodies e.g. Antisera A contains anti A antibodies

-when antisera mixes with blood sample the antibodies will bind to their specific antigen on the RBC and cause clumping or agglutination

e.g.
Antisera A will have anti A antibodies and so will agglutinate with blood types A and AB (as these express A antigens on RBC surface)

It will not react with blood types B or O as these do not express A antigens on RBC surface

Question 33

what order is blood tested in?

Answer 33

-first use antisera to figure out ABO group and rhesus status
-second to antibody screening using regeant red cells (need to first know group so know what type of regent red cells to use)

Question 34

explain antibody screening using regent red cells

Answer 34

After ABO grouping is figured out must do antibody screening

-patients plasma is tested against several reagent red cells which express a known range of antigens
-to identifiy antibodies in plasma

-use INDIRECT ANTIGLOBULIN TEST : add anti-human globulin (AHG) to plasma/ red cell suspension to facilitate agglutination
-agglutination indicates presence of an antibody

Question 35

what is a cross match used for?

Answer 35

checking if donor cells are compatible with patient plasma

-use indirect anti-globulin test and agglutination indicates cells are incompatible with patient plasma

Question 36

disadvantage of platelets being stored at room tmperature?

Answer 36

higher risk of infection