Direct Antiglobulin Testing Flashcards

1
Q

AB ID important steps
a
rule
negative
ID/AHG

A

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

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2
Q

Indirect testing

A

in vitro

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3
Q

Direct testing
example

A

In vivo (example DAT)

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4
Q

AB screen test
what kind of test

what makes it indirect?

A

IAT

cells and plasma make it indirect test

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5
Q

What are other IAT tests?
a,c,w

A

Autocontrol, Crossmatch, Weak D

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6
Q

Direct Antiglobulin test

when is it ordered?
h
p
t
c

A

hemolysis present
positive autocontrol
transfusion rxn workup
cordblood eval

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7
Q

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

A

hemolytic anemia by immune process 83% with symptoms

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

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8
Q

Autocontrol

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

A

indirect

has incubation step
in vitro
IDs presence in plasma

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9
Q

interpretations of autocontrol

positive

agg
could be?
t?
a?
c?

A

agglutination with ab
could be igG
transfused cells
auto immune
contaminant

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10
Q

Interpretations of autocontrol

negative

no?
DAT?
Not reactive with?

A

no agglutination at AHG

DAT likely negative for IgG
not reactive w old cells

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11
Q

DAT test
no?
in?
IDs?
Against?

A

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

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12
Q

AHG is polyspecific….

A

antihumanglobulin (IgG and monoclonal)

anticompliment (monoclonal)

failure to add rgnt can cause false neg

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13
Q

Check cells
coombs
compliment

A

coombs: Anti-IgG
compliment: C3 affected

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14
Q

Positive C3b

A

hemolysis due to compliment

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15
Q

Positive IgG

A

immune process stimulation

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16
Q

Anti IgG positive
Anti C3D positive

A

WAIHA, HTR

17
Q

Anti IgG Positive
Anti C3D Negative

A

WAIHA, HTR, HDN

18
Q

Anti IgG negative
Anti C3D positive

A

CAD, PCH

19
Q

Elution
does what to RBCs?
very large?

Cell is no longer viable after?

Whats best for ABO?

A

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)

20
Q

What process must be controlled in elution?

A

wash step must be controlled

expect a negative result

21
Q

Adsorption
removes?
purposely?

A

removing autoab in order to ID underlying allo ab

purposely coat red cells w ab

22
Q

Autoabsorption
used to?
When pt havent been?

A

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

23
Q

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

A

use to seperately ID Ab activity

used when a pt has been transfused

risk may accidently rule out high incidence ab

24
Q

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

Allo absorbtion? test what?

A

expect negative result for autoabsorption - plasma w pt cells

alloadorption: test absorbed plasma with screen cells
expect neg agglut

25
Q

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

A

mix of self and non self

ABO may show mixed field

elution will show transfusion rxn

26
Q

Mixed fields in the forwards type could mean?

A

pt was given O negative blood

27
Q

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

A

pt cells

28
Q

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

A

Testing the last wash with screen cells