Direct Antiglobulin Testing

Question 1

AB ID important steps
a
rule
negative
ID/AHG

Answer 1

1.) Autocontrol
2.) Rule out = no rxn…all sign ab
3.) all blood given must be negative (do phentoype)
4.) ID non ABO ab in system, AGH crossmatch compatible units

Question 2

Indirect testing

Answer 2

in vitro

Question 3

Direct testing
example

Answer 3

In vivo (example DAT)

Question 4

AB screen test
what kind of test

what makes it indirect?

Answer 4

IAT

cells and plasma make it indirect test

Question 5

What are other IAT tests?
a,c,w

Answer 5

Autocontrol, Crossmatch, Weak D

Question 6

Direct Antiglobulin test

when is it ordered?
h
p
t
c

Answer 6

hemolysis present
positive autocontrol
transfusion rxn workup
cordblood eval

Question 7

DAT
predicitive of?
what disease?
how many pts have pos DAT/no clin sympt?

Answer 7

hemolytic anemia by immune process 83% with symptoms

1-15% of pts have pos DAT and no clinical symtoms

Question 8

Autocontrol

principle
what kind of test?
has?
in?
IDs?

Answer 8

indirect

has incubation step
in vitro
IDs presence in plasma

Question 9

interpretations of autocontrol

positive

agg
could be?
t?
a?
c?

Answer 9

agglutination with ab
could be igG
transfused cells
auto immune
contaminant

Question 10

Interpretations of autocontrol

negative

no?
DAT?
Not reactive with?

Answer 10

no agglutination at AHG

DAT likely negative for IgG
not reactive w old cells

Question 11

DAT test
no?
in?
IDs?
Against?

Answer 11

no incubation
in vivo
IDs presence on cell
against Fc region of Ab

Question 12

AHG is polyspecific….

Answer 12

antihumanglobulin (IgG and monoclonal)

anticompliment (monoclonal)

failure to add rgnt can cause false neg

Question 13

Check cells
coombs
compliment

Answer 13

coombs: Anti-IgG
compliment: C3 affected

Question 14

Positive C3b

Answer 14

hemolysis due to compliment

Question 15

Positive IgG

Answer 15

immune process stimulation

Question 16

Anti IgG positive
Anti C3D positive

Answer 16

WAIHA, HTR

Question 17

Anti IgG Positive
Anti C3D Negative

Answer 17

WAIHA, HTR, HDN

Question 18

Anti IgG negative
Anti C3D positive

Answer 18

CAD, PCH

Question 19

Elution
does what to RBCs?
very large?

Cell is no longer viable after?

Whats best for ABO?

Answer 19

remove and ID ab coating red cells
very large aliquot of pt cells

cell is no longer viable after: acid/heat/freezing

(freezing best for ABO)

Question 20

What process must be controlled in elution?

Answer 20

wash step must be controlled

expect a negative result

Question 21

Adsorption
removes?
purposely?

Answer 21

removing autoab in order to ID underlying allo ab

purposely coat red cells w ab

Question 22

Autoabsorption
used to?
When pt havent been?

Answer 22

use to remove autoab
used when pt hasn’t been transfused

Question 23

Diffferential Absorption
used to?
used when a pt?
risks?

Answer 23

use to seperately ID Ab activity

used when a pt has been transfused

risk may accidently rule out high incidence ab

Question 24

Controls for adsorption
expect what result for autoabsorption? (what is tested)

Allo absorbtion? test what?

Answer 24

expect negative result for autoabsorption - plasma w pt cells

alloadorption: test absorbed plasma with screen cells
expect neg agglut

Question 25

Previous transfusion
mix?
ABO may show?
what will Elution show?

Answer 25

mix of self and non self

ABO may show mixed field

elution will show transfusion rxn

Question 26

Mixed fields in the forwards type could mean?

Answer 26

pt was given O negative blood

Question 27

Which is the best cell to remove auto ab in pt plasma using adsorption procedures?

Answer 27

pt cells

Question 28

For the elution procedure, which step ensures that the washing was appropriate?

Answer 28

Testing the last wash with screen cells