DAT, IAT, Elution, Crossmatch Flashcards
mono AHG
anti-IgG
poly AHG
anti-IgG and anti-C3d
polyspecific AHG pro
more sensitive (things below detectable limit)
poly AHG con
less specific
mono AHG pro
more specific
mono AHG con
less sensitive - misses Jka antibodies
DAT
polyspecific
IAT
detect antibody in patient serum
DAT
directly test RBC’s for antibody or complement that has already been formed
if DAT +
can cause HDFN, DHTR, autoimmune hemolytic anemia
reticuloendothelial system
macrophages in spleen and liver regularly remove and destroy old, damaged RBC’s
AND foreign cells
antiglobulin test false negatives
-insufficient washing
-AHG not added immediately after washing
-loss of AHG reactivity
-improper centrifugation
-improper cell suspension
antiglobulin test false POSITIVES
-complement fixes at room temp
-collected from line contaminated with dextrose
-cold autoantibody
-contaminates that look like clumping
-fibrin strands
-spinning cells too long
most false positives can be observing specimen and cell suspension
without AHG
DAT limitations
DAT can be negative if there is complete destruction of RBC’s in an immune hemolytic process (ABO incompatibility)
all healthy RBC’s have a small amount
of bound antibody and complement
reasons for positive for DAT
HDFN, HTR, autoimmune/ drug induced hemolytic anemia
follow up for + DAT
check patient’s history (recent transfusion, new drug)
-DAT but with IgG or C3d
-elution and antibody ID
-RBC phenotyping on patient or transfused unit
elution
release, concentrate and purify antibodies bound to RBC’s (end with freed antibody)
elution tech
temp dependent– IgG
WASH and resuspend cells in saline or saline and albumin
alter pH
acid elution
organic solvents
elution 45
gentle method, RBC’s remain intact
elution 56
total elution, allows for antibody ID
most critical step of elution
initial wash; remove unbound immunoglobulins
elution control
last wash supernatant should be saved and testing in parallel with elute to detect presence of unbound antibody
LAST WASH should be nonreactive otherwise invalid
cord blood testing
done on infants of mothers who are group O or D-
crossmatching
RBC unit should be tested with compatibilty with recipient plasma
plasma units should be selected for compatibility but
require no crossmatch
plasma cross match with patient cells
minor crossmatch
if a patient has no history of antibody and a negative screen they
only need IS crossmatch
if patient has antibody history or positive screen
FULL AHG crossmatch
