Blood group antibody screening

Question 1

Unexpected antibodies occurs due to

Answer 1

Blood transfusions,
Pregnancy

Question 2

Clinically significant antibodies

Answer 2

IgGs, reactive at 37C.
Can cause haemolytic transfusion reactions and Haemolytic disease of fetus and newborn.

Question 3

How is antibody screen performed?

Answer 3

Indirect antiglobulin test
Patient plasma is put against 3x screening cells in AHG gel.

Question 4

Antibody screening test set up

Answer 4

1. Add 50uL of (0.8%) screening cells 1/2/3 to appropriate microtubule.
2. Add 25uL of patient plasma to each microtubule.
   Add 25uL of Weak Anti-D/Inert AB to control microtubules.
3. Incubate at 37C for 15-20mins.
4. Centrifuge for 10 mins.
   Controls=
5. Anti-D (positive control) = 2/3 screening cells should be positive.
6. Inert AB (negative control) = all screening cells are group O so will not react with Anti-A/B.

Question 5

What gel is used for antibody screening?

Answer 5

LISS/Coombes gel
Green label.

Question 6

Unexpected Antibody screening controls

Answer 6

Anti-D
(2/3 screening cells are D+ so should be positive)
Inert AB (screening cells are O+ so all should be negative)