9. laboratory tests

8/9/2019 9. Laboratory Tests

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Definition

Series of testingprocedures and processes

To ensure the bestpossible results of a bloodtransfusion

Cannot guarantee RBCviability

Cannot totally eliminatetransfusion reactions


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Pre-transfusion testing

ID, collection & prep ofsamples

Donor sample:

By collecting facility: ABO &Rh grouping, diseasetransmission, antibody ID if w/possible sensi.

By transfusing facility: confirmABO & Rh using attachedsegment

Patient sample:

ABO & Rh, antibody screening


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Crossmatching

Importance ofSerologicXmatch:

1. Final ABO compatibilitycheck

2. Antibody against untestedAg

Can be eliminated if(a.k.a. Type & Screen):

1. No clinically significant

antibodies were detected


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Serologic Crossmatch


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Serologic Crossmatch


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Crossmatching

Computer Crossmatch

Emergency Crossmatch

Abbreviated Incomplete crossmatch


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Other considerations

Non ABO specifictransfusion

Plasma products

Intrauterine transfusions Neonatal transfusions

Massive transfusions

Specimens with prolongedCT

Autologous transfusion

Effective blood utilization

Reidentification of atient


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Definition

Red cells that areagglutinated by a largeproportion of adult human

sera regardless of bloodgroup.

Usually non-reactive with

autologous serum

Acquired or inherited


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Categories

Microbial associated(Transient, common)

T, Tk, Acquired-B, Th, VA

Non-microbial associated(permanent & irreversible)

Tn, CAD, NOR

HEMPAS (hereditaryerythroblasticmultinuclearity w/ a positive

acidified serum) a chronic


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Laboratory Testing

Detection

Not easily detected:

Natural polyagglutinins are

destroyed during themanufacturing process

Antibodies are low in titer

Apparent duringcrossmatching (esp minor)


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Laboratory Testing

Confirmation

RBC should be tested withseveral cord blood sera and

with several normal groupAB adult sera

Classification

Enzymes Lectins


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Laboratory Testing

Absorption

Enzymes

Cord sera Aged sera

Dilution

Sulfhydril compounds Absorption & elution


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Adsorption

Removal of antibody fromserum by absorption withred cells of appropriate

phenotype

Useful in:

Removal of unwanted

antibody (e.g. Autoantibody,interference with reagent)

Separation of multiple

antibodies


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Elution

Release of antibodymolecules from red cellmembrane

Done by disruptingantigen or by changingconditions to favordissociation of Ag-ab

Common methods: Heat technique (Landsteiner

& Miller)

Ether technique (Rubin)


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HemeagglutinationInhibition

To demonstrate presenceof soluble substance inbody fluids


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Neutralization

To inactivate unwantedantibodies


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Panel Cell Testing


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Definition

Quantification of antibodypresent

Performed when the ff arenot available:

Flow cytometry

Radioimmunoassay

ELISA

9. laboratory tests

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