Direct Antiglobulin Testing Flashcards
AB ID important steps
a
rule
negative
ID/AHG
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
Indirect testing
in vitro
Direct testing
example
In vivo (example DAT)
AB screen test
what kind of test
what makes it indirect?
IAT
cells and plasma make it indirect test
What are other IAT tests?
a,c,w
Autocontrol, Crossmatch, Weak D
Direct Antiglobulin test
when is it ordered?
h
p
t
c
hemolysis present
positive autocontrol
transfusion rxn workup
cordblood eval
DAT
predicitive of?
what disease?
how many pts have pos DAT/no clin sympt?
hemolytic anemia by immune process 83% with symptoms
1-15% of pts have pos DAT and no clinical symtoms
Autocontrol
principle
what kind of test?
has?
in?
IDs?
indirect
has incubation step
in vitro
IDs presence in plasma
interpretations of autocontrol
positive
agg
could be?
t?
a?
c?
agglutination with ab
could be igG
transfused cells
auto immune
contaminant
Interpretations of autocontrol
negative
no?
DAT?
Not reactive with?
no agglutination at AHG
DAT likely negative for IgG
not reactive w old cells
DAT test
no?
in?
IDs?
Against?
no incubation
in vivo
IDs presence on cell
against Fc region of Ab
AHG is polyspecific….
antihumanglobulin (IgG and monoclonal)
anticompliment (monoclonal)
failure to add rgnt can cause false neg
Check cells
coombs
compliment
coombs: Anti-IgG
compliment: C3 affected
Positive C3b
hemolysis due to compliment
Positive IgG
immune process stimulation