1. Pre transfusion testing

Question 1

In general, pre -transfusion testing consists of

Answer 1

group and hold/group and screen (ABO RhD group and antibody screen), and comparison of historical findings to new results

Question 2

purpose of pre -transfusion testing:

Answer 2

1. to select blood components for the patient that will have acceptable survival when transfused
2. To confirm ABO compatibility between component and recipient.
3. and determine any clinically significant antibodies

Question 3

sample validity of 72hrs applies to which patients?

Answer 3

-pregnant women
-patient who has had a tx rx
- patient had an HPC transplant
ALL WITHIN LAST 3 MONTHS

Question 4

why is a short 72 hr sample validity applied to these patients?

Answer 4

Because these patients are likely to rapidly make antibodies in response to stimulation by tx red cells or pregnancy.

Question 5

sample validity of 7 days applies to which patients?

Answer 5

All except recently pregnant, recently transfused and recently transplanted allogeneically (HPC)

Question 6

How are A, B AB and O blood groups determined?

Answer 6

By the type of antigen on the red cells

Question 7

Are ABO antibodies IgG or IgM?

Answer 7

IgM, but O type patients have an anti-A,B that is IgG

Question 8

ABO grouping is determined by

Answer 8

forward and reverse grouping.

Testing for antigens and antibodies respectively

Question 9

Which red cells is selected in emergency situations?

Answer 9

Haemolysin negative, O RhD negative red cells.

Question 10

When would you perform a second grouping(ABO and D)?

Answer 10

When the patient has not had a previous historical blood grouping.

Question 11

Clinically significant antibodies are generally what?

Answer 11

Reactive at 37C in the IAT test + ABO

Question 12

Why are antibody screening cells group O?

Answer 12

Screening is to detect clin sig antibodies other than ABO, and group O screening cells do not have antigens on the red cells that will stimulate a rx due to the patient’s ABO antibodies.

Question 13

What does it mean when antibodies show ‘dosage’?

Answer 13

They only show a reliable reaction with cells that express homozygosity of the antigen on the red cell (ie Cc not CC)

Question 14

Requirements of screening cells:

Answer 14

Between the three screening cells they must express antigens to all common clin sig antibodies, and one cell of each set must express homozygous RhCE, Duffy, Kidd and Ss to detect presence of antibodies that show dosage.

Question 15

What does phenotyping mean?

Answer 15

Antigen typing the red cells against reagent antiserum to determine their phenotype (excl ABO)