Test 3: anticoagulants Flashcards
How do most anticoagulants work?
Prevent clotting by enhancing the action of natural inhibitors, or by complexing with calcium
-anticoagulants are selected for the effects they will produce on cellular morphology, or by the manner which they affect coagulation processes
______ is used for most routine, hematology tests, while _______ is used for most routine coagulation tests.
EDTA, Na citrate
Anticoagulant that works by preventing the coagulation of blood by chelating calcium, and thus making it unavailable for participation in the clotting process.
EDTA
-forms insoluble calcium salts in the process
Why is EDTA not used for coagulation?
Because it inhibits fibrinogen and thrombin, and it degrades factor V
EDTA also prevents ___________ aggregation in most patient specimens.
Platelet
-Used for some platelet function tests and platelet counts
EDTA-caused platelet clumping in vitro is observed in about ___% of all patients.
5
EDTA comes in what color Stoppard tubes?
-It allows for the preparation of blood films with minimal distortion of white blood cells.
Purple (lavender)
Blood collection in EDTA tubes may be use for preparation of blood films up to _____ hours post collection.
2-3
-after about three hours at room temperature degenerative cellular changes will begin to occur.
What are the degenerative changes seen after three hours at room temperature of EDTA blood?
-vacuolization of cytoplasm.
-more homogeneous appearance of nuclei.
-increase in size & disintegration rate of pits.
What will happen to blood after six hours in EDTA?
RBCs will begin to swell. This causes an increase mean cell volume (MCV), decreased erythrocyte sedimentation rate (ESR) and increased osmotic fragility.
Prevents blood clotting by potentiating endogenous inhibitors of clotting (antithrombin three, which inactivate,thrombin a major player in the coagulation cascade)
Heparin (green-Stoppard tube)
Does heparin work by cheating calcium?
NO
Why can’t heparin be used in the preparation of bloods mirrors that are to be stained with Wrights stain?
It causes the stain to have a bluish background, and it causes clumping of white blood cells and platelets
__________ is the anticoagulant of choice for osmotic fragility test, and blood gas analysis either used by syringe or a special capillary tube.
Heparin
What is the anti-coagulant of choice for routine coagulation studies?
Sodium citrate (light blue stoppered tube)
Citrate prevents blood coagulation by….
Chelating calcium
Why is sodium citrate used for tests of platelet function?
It preserves the highly labile coagulation factors, five and eight
Tube that contains sodium fluoride (or more rarely, K oxalate) -chelates calcium to prevent clotting.
Gray Stoppard tube
What tube is used for blood Alcohol levels?
Gray Stoppard tube
-fluoride also stops glycolysis
to that contains ACD (acidified citrate dextrose) for specialize cell immunology studies.
Yellow Stoppard tubes
Tube that contains no anticoagulants, used for chemistry, immunology, and blood bank assays
Red stoppers
Contain a visible gel, light silicone base layer of “serum separator”, they are equivalent to read stopper in the “order of draW”
GOST (gold) or SST (red and gray, tiger striped)
Plasma, without the clotting factors becomes….
Serum
What does plasma contain?
Water, electrolytes, glucose, fats, proteins, and dissolved gases. It also contains all the clotting coagulation factors needed for coagulation, but in the inactive zymogen form.
Other than using the correct anticoagulant for the specific laboratory assay… what else is important?
The correct amount or dilution of anticoagulant to blood specimen is extremely important. And inaccurate amount can cause inaccurate test results.
A “_________” refers to the incomplete filling of a Vacutaiber tube.
“Short draw”
The appropriate ratio for citrate is ____ part anticoagulant to ______ parts whole blood.
1, 9
- newer, purple top (sprayed) EDTA tubes are not affected by such dilution Concerns
Reasons for rejecting a blood specimen for hematology or coagulation assays?
-clotted specimen
-“short draw”
-EDTA specimen left at room temperature for longer than three hours
-hemolysis specimen
-Drawn in incorrect anticoagulant for the particular assay
which tubes should be drawn first, blood cultures or coagulation tubes?
blood culture tubes before coagulation tubes!
When a Vacutainer system is used to collect several tubes of blood, you must collect the tubes in what order? “order of draw”
Blue
GOST/Red/SST
Green
Lavender/Purple/Pink
Yellow
Gray
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