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Blood Bank Spring > Indirect Antiglobulin testing > Flashcards

Indirect Antiglobulin testing Flashcards

1
Q

What are other names for indirect antiglobulin testing?

A

AHG, coombs, enhanced ab detection

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2
Q

How do you confirm negative results?

A

use a saline control

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3
Q

What must you do for a forwards rxn that is all positive?

A

Check with saline and confirm positives

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4
Q

Frequencies:
Antigen
D ag
C ag
c ag
E ag
e ag

A

D 85 lower white
C 70 lower black
c 80 lower asian
E 30
e 98

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5
Q

What do you do to enhance weak rxn?

A

put in the fridge for IgM

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6
Q

Describe the overview of Anti-D briefly
ig
stim

A

IgG immune stimulated, warm reactive (incomplete Ab)

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7
Q

Describe the coombs test
detects?

A

detects weak/incomplete (IgG) ab using IgM to complete hemagglutination

indirect test

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8
Q

Describe the coombs rxn agglutination test
what forms a lattice
must have removal of?
incubation?
method?

A

IgG ab forms a lattice w/ IgM Anti-IgG rgn
must have removal of unbound material
incubate at body Temp
INDIRECT

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9
Q

Describe the immediate spin agglutination test
What forms a lattice
centrifuge
Plasma to cell ratio
Incubation?
binding?

A

IgM ab lattice w/o additional rgnt
Direct test
Centrifuge brings reactants close
RT
Plasma 2:1 cells 3% sol
37C
(Compliment and IgG ab more likely to bind at body temp)

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10
Q

When is the enhancement added in the coombs test?

A

added after immediate spin and before 37C incubation

this reduces zeta potential
reduces steric hinderance

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11
Q

Incomplete agglutinins

A

usually refers to IgG ab non reactive at RT

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12
Q

Coombs

A

researcher who proposed antiglobulin test method

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13
Q

Tube Test

A

classic serological method preformed with glass tubes

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14
Q

AHG

A

anti human globulin

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15
Q

IAT

A

indirect antiglobulin test

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16
Q

Enhanced ab detection

A

test method requireing more steps than immediate spin to see macroscopic agglutination

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17
Q

Briefly cover how the immediate spin test looks

A

mix cells and plasma
centrifuge
observe agglutination

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18
Q

Describe how the coombs test is done

A

mix cells and plasma
incubate 30-60 min
wash away non attached ab
add anti-ab “coombs rgn”
centrifuge

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19
Q

What happens if non attached antibodies are improperly washed?

A

false negatives

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20
Q

If antibody didnt attach to ag at incubation?

A

add red cells and plasma
incubate
wash
add anti-ab
centrifuge and read for agg
add check cells to agglut w anti-ab

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21
Q

Main keys of check cells

A

have anti-IgG coating the cell
if system isnt washed correctly, anti-ab will attach to ab left over
no binding sites left for binding w check cells

22
Q

How do you confirm a negative reaction in the wash of the coombs test?

A

check cells

23
Q

What are the 3 possible outcomes of a coombs test

A

all pos/all neg/ or invalid if check cells are negative

24
Q

When is there an invalid test in coombs?

A

When the ab in the system is bound to the rgnt not the red cell, causing negative rxn in the check cells

START OVER

25
Q

False negatives in Coombs

No agg in AHG
exc
incor
left

No agg in CC
left ov
insuff
iinsuff

A

looks like no agglut in AHG step
aged cells
excessive washing
incorrect centrifuge
left over wash dilutes

No agglut w check cells
left over ab abound check cells
insuff washing
insuff incubation

26
Q

False positives in coombs test
agg in AHG
p
f
ab
b
develop

A

looks like agg with AHG step
proteins in plasma
fibrin strands
ab attached in vivo to cells (DAT)
bacterial contam
pt devel ab to preservative

27
Q

Standardization
cell washer
monoclonal rgnt
gel test
solid phase

A

cell washer: wash step for vol and number of washes, reduces false negatives

Monoclonal: binding site, reduces false pos

Gel: test and rgnt vol, centrif, removes wash step

Solid phase: test/rgnt vol, test ag, interpret

28
Q

LISS

A

Reduce zeta potential

29
Q

PEG

A

remove water vol

30
Q

Albumin

A

increase collisions

31
Q

Bromelin

A

reduce steric hindrance

32
Q

Polybrene

A

polymer nonspecific binding

33
Q

Describe gel automated method

A

precipitation through polyacrylamide gel matrix

add red cells and plasma
incubate no wash
centrifuge no check cells

33
Q
A
34
Q

Rouleax looks like what kind of rxn on gel?

A

looks like 2+ rxn

35
Q

Describe solid phase automated method

A

adherence of ab to rbc ag on solid substance

prone to have false +

36
Q

If gel is available, why tube methods?

A

Trouble shooting - everyone goes back to tube

ref lab method - gold standard

tube method is most clinically relevant

harder but cheaper

37
Q

When do you do coombs testing?
with w
sb
cross

what kind of test? cells in?

A

with weak D, ab screen, extended cross match, autocontrol

Indirect test what has attached to the cell in VITRO

38
Q

Describe direct testing

A

what is on the cell in the body
In VIVO

is there already ab on the cell?

39
Q

Requirements for finding compatible blood
pt will rx poor if?
females?
pt with clin sign ab?

A

pt will react poorly if given incompatible blood

females of childbearing age should not be exposed to Rh incomp blood

if pt has made clinically sign immune stim ab, they should recive ag neg blood

40
Q

“Blood type” and test

A

ABO type + Rh type on pt red cells (IS)

41
Q

“Ab screen” and test

A

test for the presence of clinc sign imm stim ab in pt plasma (IAT)

42
Q

“type and cross match”

A

ABO + RH+ AB screen + sero between donor cell and pt plasma (IS-IAT)

43
Q

“extended crossmatch”
sero test between

A

sero test between donor cell and pt plasma util at body temp (IAT ONLY)

44
Q

‘Ab ID”
logical problem utilizing

A

logical problem utilizing known cells and pt plasma to ID source of unexcpet reactivity in ab screen (IAT)

45
Q

“coombs test”

A

test for ab attached to cells in VIVO (DAT)

46
Q

Reverse cells

A

mixture of donors, blood type A or B in preservative (no plasma)

47
Q

Screen cells

A

single donor type O known ag in preservative no plasma

48
Q

Antigram sheet

A

package insert that lists all interpretations of ag for screen cells

49
Q

AB screen

A

each cell represents a single donor (no mf)

if any cells in screen rx + more work needs to be done and pt will need extended crossmatch to determ compatibil w donor blood

Blood Bank Spring (18 decks)

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