Blood transfusions: Group and Screen, crossmatching, electronic tissues

Question 1

Define Group and Screen, and what are the 2 main roles?

Answer 1

Blood group and antibody screen (Group and screen): Pretransfusion lab test

1. Identifying patient’s ABO and Rh D blood groups
2. Screening patient’s serum for RBC clinically significant antibodies

Question 2

In a Group and Screen before blood transfusion, why is it important to complete the Screen?

Answer 2

There are ~300 different RBC antigens, and some antibodies are clinically significant as they are harmful to RBCs

Need to identify if the patient has any alloantibodies as these will attack donor blood

Question 3

What does a positive Antibody Screen result indicate, for blood transfusions, for blood transfusion compatibility?

Answer 3

Patient has harmful antibodies and so donor blood is incompatible

Question 4

What does a negative Antibody Screen result indicate, for blood transfusion compatibility?

Answer 4

Patient doesn’t have harmful antibodies and so donor blood is compatible

Question 5

Explain how an pretransfusion Antibody Screen test is performed in 2 steps?

Answer 5

1. Blood service sends panels of blood samples with different combinations of RBCs that express clinically significant antigens
2. Patient’s serum mixed with panels to identify complementary clinically significant antibodies (these will be the alloantibodies that patient forms)

Question 6

After Group and Screen, how long it the patient’s serum sample stored for and why?

Answer 6

7 days

For crossmatching in case transfusion is needed in that time

Question 7

Define crossmatching?

Answer 7

Series of pretransfusion tests to measure compatibility of donor blood with recipient’s serum RBC antibodies

Question 8

When crossmatching recipient and donor blood, what does no agglutination after centrifugation indicate about the compatibility?

Answer 8

Patient doesn’t have clinically significant serum antibodies

Compatible match

Question 9

When crossmatching recipient and donor blood, what does agglutination after centrifugation indicate about the compatibility?

Answer 9

Patient does have clinically significant serum antibodies

Incompatible match

Question 10

If pretransfusion crossmatching is negative, how can transfusion units be issued?

Answer 10

Don’t need physical crossmatch, so can use electronic tissue/crossmatch instead to choose correct units

Question 11

If pretransfusion crossmatching is positive, how can transfusion units be issued?

Answer 11

Need physical crossmatch again after identifying specific antibody that recipient has and transfusing that against donor red cells

Question 12

If pretransfusion crossmatching is positive, what further investigation is done?

Answer 12

Larger blood panel is used to identify specific clinically significant serum antibody that the patient has, then crossmatching lab test is performed again to detect if transfused red cells would cause agglutination reaction

Question 13

To improve blood transfusion safety, how many G&S samples are taken before confirming the ABO and RhD match?

Answer 13

2 samples

Mismatched ABO-blood can cause death within minutes due to antibodies attacking the patient’s erythrocytes (haemolysis death)

Question 14

In emergency, if patient has no group and screen records, what blood group will be transfused?

Answer 14

Group O blood

Question 15

In emergency, if patient only has 1 previous G&S sample recorded, what are the 2 options for blood transfusion units?

Answer 15

Group O blood until another sample has been taken

This blood group should be transfused to them to reserve Group O supply

Question 16

To improve transfusion safety, why does the blood bank only accept correctly-labelled samples?

Answer 16

Less risk of mixing patient details