Pretransfusion Testing Flashcards
what AABB standard address pretransfusion?
5: Process Control
serological confirmation required on whole blood, red cells, and granulocyte units
ABO group
Rh of each unit labeled Rh neg
is weak D testing required on labeling of Rh neg units
no
requirements of transfusion request
complete, accurate, legible 2 independent patient identifiers type and amount of component requested special processing requirements ordering physician
pre-transfusion testing regulated by who?
US Federal govt, accrediting agencies
sample requirement of pre-transfusion sample
2 independent patient identifiers
date and time of collection
identification of collector
when must pre-transfusion sample be drawn in relation to transfusion?
within 3 days (if transfused in last 3 months)
how long is pre-transfusion sample kept after transfusion
7 days
how long is segment of donor blood kept after transfusion
7 days
day of collection is day ___ in pre-transfusion testing
0
sample age requirement for patients who have not been pregnant or transfused in the last 90 days
no specific requirement
pre-transfusion specimen requirement for patients less than 4 months old
initial sample for ABO/Rh typing and to detect unexpected maternal red cell antibodies, no additional testing required until 4 months of age if screen is negative
crossmatch requirements for <4 months of age after pre-transfusion testing is complete
crossmatch not necessary if using O red cells if no antibodies present
if antibodies are present, crossmatch not necessary if antigen-negative red cells are used
emergency blood given to women of childbearing age
O negative
emergency blood given to women older than childbearing age and men
O positive
definition: massive transfusion
when a patient receives 10 units of blood in less than 24 hours
when is serologic XM no longer required in massive transfusion?
after 8-10 units
requirement from requesting physician for emergency released uncrossmatched blood
signed statement
requirements of blood product transfusion order from physician
specific component
amount
special requirements
purpose of compatibility testing
prevent hemolytic transfusion reaction
compatibility testing includes:
ABO/Rh of patient
antibody screen of patient
XM between patient plasma and donor red cells
AABB Standards requirement of ABO group for recipient
2 determinations of ABO group
AABB Standards requirement options for second ABO confirmation of recipient
- comparison with previous records
- testing a second sample from a second collection time with NEW VERIFICATION OF PATIENT IDENTIFICATION
- retesting original sample if patient identification was verified using validated electronic identification system
can reagent red cells for antibody detection testing be pooled
no
blood group used in antibody screen reagent cells
group O
definition: sensitization
antibody attachment to antigen
agglutination
electrostatic bonds, hydrogen bonds, hydrophobic bonds, van der Walls forces lead to binding of antibody to antigen
definition: prozone
false negative
zeta potential
ionic charges on the surface of red cells that keep them separated
strategies to enhance agglutination
decrease zeta potential enhancements increasing positive ions AHG reagents enzymes centrifugation
how does AHG encourage agglutination
overcomes electrical repulsion/zeta potential between red cells so agglutination can be observed
2 production methods of AHG
- purified gammaglobulins from human serum injected into animals to produce anti-human gammaglobulin
- monoclonal technology to make monoclonal antiglobulin reagent
monospecific
one antibody specificity
polyspecific
broad spectrum antibody specificity (IgG and C3d)
do AHG reagents contain antibodies to IgM
no
where does information about IgM coating of red cells come from in pretransfusion testing
anti-C3 (IgM activates complement)
what does IAT detect
in-vitro sensitization (binding of Ab to Ag)
what does DAT detect
in-vivo sensitization (already attached in circulation)
why is 37C incubation not included in DAT
already occurred in the body
why is 37C incubation included in IAT
temperature IgG antibodies are most active
what procedure involves washing away unbound antibody and addition of AHG
direct antiglobulin test
what procedure involves combining antibody and antigen, incubation, washing of unbound antibody, and addition of antiglobulin reagent
indirect antiglobulin test
why should a plasma sample be used for a DAT instead of a serum sample
complement is bound during the clotting process and may cause false positive DAT due to in-vitro binding of complement
QC for negative AHG test results
Coombs Control/check cells
AHG check cells reagent composition
IgG sensitized RBCs
false negatives detected by Coombs control cells
- inadequate washing
- failure to add AHG
- neutralization of AHG from residual saline or plasma proteins
antibody excess
prozone
antigen excess
postzone
false positives in AHG testing
- spontaneous agglutination
- over centrifugation
- in-vitro attachment of complement
definition: complement
series of proteins that when activated by antibody on red cells can result in lysis of those cells
sample required for complement activation
fresh serum sample less than 72 hours old
Full/Coombs serological crossmatch purpose
prevent ABO incompatibility
prevent IgG allo-antibody incompatibility
immediate spin/modified serological crossmatch purpose
prevent ABO incompatibility
requirements for IS/modified XM
negative antibody screen on current sample AND no history of clinically significant antibodies
causes of IS incompatibility
- ABO grouping error
- cold alloantibody
- cold autoantibody
- rouleaux
causes of incompatibility after 37C incubation
- alloantibody
- antibody to enhancement media
- rouleaux
causes of incompatibility at AHG
- alloantibody
- warm autoantibody
- positive DAT of donor
when can computer crossmatch be performed
- computer system has been validated for XM use
- patient meets IS criteria
- current sample ABO/RH in LIS
- 2 ABO/RH on patient both in LIS
- donor cells retyped and results in LIS
are antigen negative units required for patients with clinically insignificant antibodies
no
are antigen negative units required for patients with clinically significant antibodies
yes
ABO requirement of whole blood selection
ABO identical to recipient or low-titer group O
ABO requirement of RBC selection
ABO compatible with recipient plasma
ABO requirement of granulocyte selection
ABO compatible with recipient plasma
ABO requirement of plasma selection
ABO compatible with recipient RBC
ABO requirement of platelet selection
all ABO groups acceptable but ABO identical or compatible with recipient RBCs preferred
ABO requirement of cryoprecipitate selection
all ABO groups acceptable
requirements of unit tag
attached securely to bag
2 patient identifiers
donor unit number
compatibility testing result
required physician orders for blood administration
- request of product preparation from blood bank
- request of product transfusion
blood administration IV access for adults
18-20 gauge needle
blood administration IV access for kids
22-24 gauge needle
IV solutions compatible with blood products
- 0.9% normal saline
- Normosol-R, pH 7.4
- Plasma-Lyte-A, pH 7.4
standard blood administration filter
170-260 microns
blood product transfusion must be complete in what timeframe
4 hours
definition: polyclonal antibodies
antibodies that bind to slightly different regions on the same antigens (different epitopes)
definition: monoclonal antibodies
antibodies formed from a single type of plasma cell and always bind to a single epitope
