Test 3: anticoagulants

Question 1

How do most anticoagulants work?

Answer 1

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

Question 2

______ is used for most routine, hematology tests, while _______ is used for most routine coagulation tests.

Answer 2

EDTA, Na citrate

Question 3

Anticoagulant that works by preventing the coagulation of blood by chelating calcium, and thus making it unavailable for participation in the clotting process.

Answer 3

EDTA

-forms insoluble calcium salts in the process

Question 4

Why is EDTA not used for coagulation?

Answer 4

Because it inhibits fibrinogen and thrombin, and it degrades factor V

Question 5

EDTA also prevents ___________ aggregation in most patient specimens.

Answer 5

Platelet

-Used for some platelet function tests and platelet counts

Question 6

EDTA-caused platelet clumping in vitro is observed in about ___% of all patients.

Answer 6

5

Question 7

EDTA comes in what color Stoppard tubes?
-It allows for the preparation of blood films with minimal distortion of white blood cells.

Answer 7

Purple (lavender)

Question 8

Blood collection in EDTA tubes may be use for preparation of blood films up to _____ hours post collection.

Answer 8

2-3

-after about three hours at room temperature degenerative cellular changes will begin to occur.

Question 9

What are the degenerative changes seen after three hours at room temperature of EDTA blood?

Answer 9

-vacuolization of cytoplasm.
-more homogeneous appearance of nuclei.
-increase in size & disintegration rate of pits.

Question 10

What will happen to blood after six hours in EDTA?

Answer 10

RBCs will begin to swell. This causes an increase mean cell volume (MCV), decreased erythrocyte sedimentation rate (ESR) and increased osmotic fragility.

Question 11

Prevents blood clotting by potentiating endogenous inhibitors of clotting (antithrombin three, which inactivate,thrombin a major player in the coagulation cascade)

Answer 11

Heparin (green-Stoppard tube)

Question 12

Does heparin work by cheating calcium?

Answer 12

NO

Question 13

Why can’t heparin be used in the preparation of bloods mirrors that are to be stained with Wrights stain?

Answer 13

It causes the stain to have a bluish background, and it causes clumping of white blood cells and platelets

Question 14

__________ is the anticoagulant of choice for osmotic fragility test, and blood gas analysis either used by syringe or a special capillary tube.

Answer 14

Heparin

Question 15

What is the anti-coagulant of choice for routine coagulation studies?

Answer 15

Sodium citrate (light blue stoppered tube)

Question 16

Citrate prevents blood coagulation by….

Answer 16

Chelating calcium

Question 17

Why is sodium citrate used for tests of platelet function?

Answer 17

It preserves the highly labile coagulation factors, five and eight

Question 18

Tube that contains sodium fluoride (or more rarely, K oxalate) -chelates calcium to prevent clotting.

Answer 18

Gray Stoppard tube

Question 19

What tube is used for blood Alcohol levels?

Answer 19

Gray Stoppard tube

-fluoride also stops glycolysis

Question 20

to that contains ACD (acidified citrate dextrose) for specialize cell immunology studies.

Answer 20

Yellow Stoppard tubes

Question 21

Tube that contains no anticoagulants, used for chemistry, immunology, and blood bank assays

Answer 21

Red stoppers

Question 22

Contain a visible gel, light silicone base layer of “serum separator”, they are equivalent to read stopper in the “order of draW”

Answer 22

GOST (gold) or SST (red and gray, tiger striped)

Question 23

Plasma, without the clotting factors becomes….

Answer 23

Serum

Question 24

What does plasma contain?

Answer 24

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.

Question 25

Other than using the correct anticoagulant for the specific laboratory assay… what else is important?

Answer 25

The correct amount or dilution of anticoagulant to blood specimen is extremely important. And inaccurate amount can cause inaccurate test results.

Question 26

A “_________” refers to the incomplete filling of a Vacutaiber tube.

Answer 26

“Short draw”

Question 27

The appropriate ratio for citrate is ____ part anticoagulant to ______ parts whole blood.

Answer 27

1, 9

• newer, purple top (sprayed) EDTA tubes are not affected by such dilution Concerns

Question 28

Reasons for rejecting a blood specimen for hematology or coagulation assays?

Answer 28

-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

Question 29

which tubes should be drawn first, blood cultures or coagulation tubes?

Answer 29

blood culture tubes before coagulation tubes!

Question 30

When a Vacutainer system is used to collect several tubes of blood, you must collect the tubes in what order? “order of draw”

Answer 30

Blue
GOST/Red/SST
Green
Lavender/Purple/Pink
Yellow
Gray

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