LEC 6 0 HEMOSTASIS LABORATORY TESTING Flashcards by CHARLENE SAN JOSE

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Most hemostasis procedures are performed on what type of specimen

platelet-poor plasma (PPP, plasma whose platelet count is less than
10,000/uL)

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At the moment of collection, blood is mixed
with sodium citrate anticoagulant and is maintained as well
mixed whole blood for assays that require whole blood such as

platelet function tests

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centrifuging mixed blood to produce platelet-rich plasma (plt count is approx 200,000/ul) is used in what assays

light transmittance platelet aggregometry

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platelet-poor-plasma is used in what assays

clot based assays/coagulation studies

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before performing blood collection, the clinician must ask about the clotting and bleeding history, as well as the blood group O people.

What is the significance of asking blood group O people for their blood type?

(group O people have a higher von Willebrand disease prevalence)

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Bleeding and clotting characteristics come next, including ________, and whether events are
spontaneous or follow an injury or a surgical or dental proce
dure.

location, frequency, volume

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aside from assessing their bleeding history, conditions, as well as the bleeding characteristics, what comes next to assess?

2-week drug history

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assessing the 2-week drug history includes ______

anticoagulants (blood thinners)
antiplatelet drugs aspirin and non-steroidal anti-inflammatory drugs)
contraceptives
hormone replacement therapy (thrombotic)

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The patient is also asked about over
the-counter remedies and dietary supplements, such as ______

ginger
garlic
vitamin K
St. John’s wort

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If the patient is taking over
the-counter remedies and dietary supplements, it is instructed to discontinue at least how many days or weeks prior to blood collection

7 days or 1 week

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Lastly, the clinician examines the patient for evidence of bleeding; ___ and ____

bruises and swelling

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_______ may be employed to enhance bleeding history accuracy

Standardized bleeding assessment tools (BAT)

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Patients need only fast under arranged circumstances
but are advised to avoid caffeine and exercise for ______

2 hrs

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Patients need only fast under arranged circumstances
but are advised to avoid caffeine and exercise for 2 hours and
smoking for ________ before collection.

30 minutes

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Patients need only fast under arranged circumstances
but are advised to avoid caffeine and exercise for 2 hours and
smoking for 30 minutes before collection. Patients should be
inactive for _______ before collection.

5 minutes

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if there a reason to anticipate excessive bleeding - for instance, if the patient has multiple bruises , mentions a tendency to bleed, and possesses high BAT score - we must monitor the venipuncture site from the usual 1 mn to how many minutes before we dismissed the patient

5 mns

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In the case of small, scarred, or fragile veins, the collector may fit a _____
needle infusion tube to a syringe, which enables the collector to
reduce and control the negative collection pressure.

23-gauge Luer-adapter needle or 23-gauge “butterfly”

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Adult with good veins, collecting not more than 25 ml of blood is preferred to be collected using what needle gauge

20 or 21 needle gauge, thin walled, 1.0 or 1.25 inches long

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Adult with good veins, collecting more than 25 ml of blood is preferred to be collected using what needle gauge

19 gauge needle

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child or adult with small fragile or hardened veins are preferred to be collected using what gauge of needle

23 gauge, winged needle set; collect with small evacuated tubes or syringe

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the transferring of blood from syringe to tube is done using

19 gauge safety transfer unit; slowly inject through tube closure

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Most hemostasis specimens are collected in plastic blue-closure (blue-top, blue-stopper) sterile evacuated blood collection
tubes containing a measured volume of buffered ______
anticoagulant.

sodium citrate

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what type of tube for collecting blood is suitable but its use is declining due to possible breakage and consequent risk of exposure to bloodborne pathogens

Siliconized (plastic-coated) glass tubes

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are Tubes of uncoated soda-lime glass unsuitable for collection?

no po

content and percent of sodium citrate used

0.105 - 0.109 M (3.2%) sodium citrate

why sodium citrate is the best anticoagulant for most hemostasis testin?

sodium citrate binds calcium ions to prevent coagulation and the buffer stabilizes the specimen pH as long as the tube closure remains in place

Upon collection, the anticoagulant solution mixes with blood to produce what ratio

9:1 ratio

the collection ratio of 9:1 has what legends

9 parts whole blood to 1 part anticoagulant

In most cases, 0.3 mL of anticoagulant mixes with _______ mL of whole blood

2.7

The ratio yields a final citrate concentration of _______ of anti coagulant in whole blood

10.5 to 10.9 mM

The 9:1 blood-to-anticoagulant ratio is effective, provided the patient’s hematocrit is _______

55% or below

formula for computing sodium citrate anticoagulant in patients who have hct of 55% and above

C = (1.85 10^-3 ) (100 - HCT) V

do we need to increase the anticoagulant for specimens from patients with anemia, even when the hematocrit is less than 20%?

no, there is no existing evidence suggesting a need for increasing the volume of sodium citrate

why do practitioners do not use ethylenediaminetetraacetic acid for coagulation testing?

EDTA irreversibly chelates calcium ions EDTA doesn't preserve labile factors inhibits thrombin-fibrinogen reaction

calcium ion chelation with citrate is can be reversed with the addition of

calcium chloride

If EDTA is not used for coagulation test, what can we use it for?

complete blood count including PLATELET COUNT

________ (anticoagulant) specimens have never been validated for plasma coagulation testing but may be necessary to produce accurate platelet counts in cases of PLATELET SATELLITISM (satellitism) as a substitute for specimens collected in EDTA.

Heparinized (green closure)

reason why we are not using heparin for hemostasis testing?

binds with anti-thrombin III inhibits all coagulation reaction

if heparin is not for coagulation testing, what are the assay or test we can use heparin?

platelet retention/glass bead retention test

aside from platelet count, what is the use of EDTA in hemostasis testing?

EDTA may be required for specimens used for molecular diagnostic testing, such as testing for the FACTOR V LEIDEN MUTATION.

tubes used for molecular diagnostic such, as specified by institutional protocol

acid citrate dextrose (ACD, yellow closure) and dipotassium EDTA (K2EDTA, white closure

anticoagulant in yellow closure

acid citrate dextrose (ACD)

dipotassium EDTA (k2EDTA ) is an anticoagulant in what closure

dipotassium EDTA (k2EDTA )

tubes suppress in vitro platelet or coagulation activation for specialty assay

Citrate theophylline adenosine dipyridamole (CTAD, blue closure)

what is the in vitro platelet or coagulation activation specialty assay that Citrate theophylline adenosine dipyridamole (CTAD, blue closure) is used for?

platelet activation marker platelet factor 4 (PF4) or coagulation activation marker thrombin-antithrombin complex (TAT)

Nonadditive tubes include _____ (but not plastic) tubes and clear closure plastic tube

red-closure glass

what should we do if w non additive tubes are unavailable?

the phlebotomist may use and discard a preliminary blue-closure tube when following an additive tub

this venipuncture procedure is Preferred over syringe method

evacuated tube system

this venipuncture procedure allows the Blood directly mixes with anticoagulant

evacuated tube system

ORDER OF DRAW

oRed top tube oLight blue oEDTA oPlastic syringe

in Syringe Method what is the use of first syringe

sample collected is discarded or can be used for other serological test

in syringe method, what is the use of 2nd syringe

collected for coagulation studies

2 reasons why we need to discard the first syringe in 2-syringe method

prevent contamination maintains accurate result

what type of pressure is in evacuated tube that allows to collect correct volume of blood

negative internal pressure

why do we need to prevent having shortdraw in coagulation testing

generates erroneously PROLONGED clot-based coagulation test results because the excess anticoagulant neutralizes test reagent calcium

what should we do in short draw specimen

Short-draw specimens are discarded, and a fresh specimen is collected.

Evacuated tubes are designed so that the _____ pressure collects the correct volume of

negative internal

. In most cases the volume of blood collected must be within ________% of the calibrated volume

how does the phlebotomist compensates for the internal volume of the tubing using butterfly winged set

by collecting and discarding a non additive tube or a blue closure tube. This step ensures that the needle set tubing is filled with fresh patient blood before the hemostasis specimen is collected and avoids an inadvertent short draw

Clotted specimens are useless for hemostasis testing, even if the clot is small true or false

true

how many invert we need right after mixing the blood to anticoagulant

at least 3 times

Excessive specimen agitation, called “_______,” causes hemolysis (RBC rupture), procoagulant activation, and platelet activation

cocktail shaking

During blood collection, the phlebotomist must remove the tourniquet within 1 minute of its application to avoid ____, which slows venous flow

stasis

_________ results in endothelial cell activation and hemoconcentration with the local accumulation of coagulation factors V, VII, VIII, XII, and von Willebrand factor (VWF), which may falsely shorten clot-based coagulation test results.

Stasis

collecting blood in vascular access device Before blood is collected for hemostasis testing, the line must be flushed with______ of saline,

5 mL

collecting blood in vascular access device Before blood is collected for hemostasis Before blood is collected for hemostasis testing, the line must be f lushed with 5 mL of saline, and the first ______ of blood, or six times the volume of the blood collection tube, must be collected and discarded.

5 mL

example of vascular access device

IV catheter, cannula, heparin or saline locks, peripherally inserted central catheters, central venous catheters, dialysis catheters

site of capillary function

off center of the fingertip and perpendicular to the fingerprint lines

what type of blood is ideal for capillary puncture coagulation test

free flowing blood

Further, hemolysis interferes with _______ result

optical endpoint coagulometer

LIPEMIC OR ICTERUS SAMPLE interfere with __ method

chromogenic substrate

in a lipemic or icteric sample. The practitioner must employ an _________ instrument.

electro-mechanical detection method

Storage at REFRIGERATOR (1-6*c) temperatures causes _____

precipitation of large von Willebrand factor multimers, activation of coagulation factor VII, activation of platelets, and destruction of platelet integrity.

Storage at above standard room temperature (>25*C) causes coagulation __ to deteriorate.

factors V and VIII

what will happen if the CO2 diffused due to unsealing the collection tube?

pH rise and results to falsely prolonged PT and PTT

relationship of pH to bleeding

rise in pH increase PT and PTT alkaline blood means bleeding

Specimens are maintained at ambient temperature, ____, never at refrigerator temperatures or on ice

15° C to 25° C

Specimens collected for PTs may be held uncentrifuged or centrifuged at 15° C to 25° C and tested within ____ hours of the time of collection

what pathway is related to PT?

PTEX PT = EXTRINSIC PATHWAY (FIII and FVII)

what pathway is related to PTT?

intrinsic and common pathway

Specimens collected for PTTs and most other clot-based assays are also held uncentrifuged or centri fuged at 15° C to 25° C, but they must be tested within ___ hours of time of collection.

4 hrs

If a patient is receiving unfractionated heparin (UFH) therapy, PTT specimens must be centrifuged within 1 hour of the time of collection to avoid depletion of the ________

heparin

Centrifuges that are used to prepare hemostasis specimens must maintain a temperature of __________

15° C to 25° C

If any plasma-based hemostasis assay cannot be completed within the prescribed interval, the practitioner must centrifuge the specimen within ________ hour of collection

1 hour

The practitioner immediately transfers the PLASMA by plastic pipette to a __

plastic freezer tube

are we allowed to use glass containers for plasma-based hemostasis upon separation of plasma

no, glass stimulates the intrinsic coagulation pathway

The freezer tube for plasma based hemostasis is stored at ____ for up to 2 weeks

-20*C

The freezer tube for plasma based hemostasis is stored at ____ for long term storage (6 months )

-70*C

PT with no UFH specimen stability

test within 24 hr maintain upright and sealed

PTT with no UFH specimen stability

test within 4 hr maintain upright and sealed

PTT with monitoring UFH

centrifuge to separate plasma within 1 hr, test within 4 hr

PT with monitoring UFH

centrifuge to separate plasma within 1 hr, test within 4 hr

factor assays specemin stability

test within 4 ht maintain upright and sealed

optical platelet aggregometry using PRP specimen stability

wait within 30mn after centrifugation and test within 4hr of collection

To avoid cryoprecipitation of VWF, specimens may not be frozen and thawed more than once true or false

true

Aggregometry should be started immediately and must be completed within ______ hours of specimen collection (for undiminished ex vivo platelet activity).

whole blood specimen for platelet aggregometry is collected at ___ in ___ temperature

3.2% sodium citrate and held at 15° C to 25° C until testing

Most specimens for whole-blood aggregometry are mixed ____ with normal saline before testing, although if the platelet count is less than 100,000/mL the specimen is tested undiluted

1:1

___ are designed to test PRP (Platelet-Rich Plasma)

Light-transmittance (optical) platelet aggregometers

platelet poor plasma has how many platelets?

less than 10,000/ul or < 10 x 10^9 plt/L

centrifugation of PPP

10-15 mn, 2000 - 2500 rpm

PPP is tested within

2 hrs

refrigerated temp of PPP

no longer 4 hrs

freezing temp of PPP

-20 to -70*C

PPP is used in what studies

coagulation studies

Platelet Rich Plasma (PRP) has how many PLTS

250 x 10 ^9 PLT/l

CENTRIFUGATION of PRP

10-15 mns 60-100 rpm

PRP is stored at what temp

room temp

PRP is used in what studies

platelet studies

How aspirin affects hemostasis testing?

inhibits cyclooxygenase

in plt aggregation test, the patient must refrain taking aspirin prior the test for howmany days

7 days

for bleeding time, patients taking aspirin must refrain from taking it prior the collection for how many days

1 day

how heprarin affects hemostasis testing

affects cyclooxygenase inhibits most clotting factors

antagonist of prothrombin group and vitamin K dependent clotting factors

warfarin/coumadin

it prevents gamma carboxylation of vitamin K on clotting factors

warfarin/coumadin

it alters blood vessels and induces hemolysis

penicillin

most potent penicillin capable of affecting platelet function

carbenicillin

it prematurely activates clotting process (extrinsic pathway )

tissue thromboplastin contamination

this factor is must be activated only when the reagent is added

tissue thromboplastin

a factor that affects the specimen and is associated with collagen for in vitro activation of clotting process

glass surfaces

the factors that prematurely activates at ref temp 4*C

factor VII and Factor XI

factors that deteriorates if left at room temp for extended period of time

labile factors factor V and factor VIII

how hemolysis affects sample and testing

releases tissue thromboplastin like substance that will activate clotting system release ADP that causes platelet aggregation

how tourniquet affect hemostasis testing

causes venous stasis activates clotting factors

increased pH effect to hemostasis testing

associated with loss of carbon dioxide that deteriorates clotting factors sample must be unopened and tested within 6 hrs

effect of polycythemia vera in hemostasis testing

increases hematocrit by >50% prolongs clotting time test

incomplete filling of tubes can result to ___

increased amount of citrate (prolonged)