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HEMATOLOGY 2 > LEC 6 0 HEMOSTASIS LABORATORY TESTING > Flashcards

LEC 6 0 HEMOSTASIS LABORATORY TESTING Flashcards

1
Q
A
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2
Q

Most hemostasis procedures are performed on what type of specimen

A

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

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3
Q

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

A

platelet function tests

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4
Q

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

A

light transmittance platelet aggregometry

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5
Q

platelet-poor-plasma is used in what assays

A

clot based assays/coagulation studies

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6
Q

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?

A

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

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7
Q

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

A

location, frequency, volume

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8
Q

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

A

2-week drug history

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9
Q

assessing the 2-week drug history includes ______

A

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

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10
Q

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

A

ginger
garlic
vitamin K
St. John’s wort

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11
Q

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

A

7 days or 1 week

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12
Q

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

A

bruises and swelling

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13
Q

_______ may be employed to enhance bleeding history accuracy

A

Standardized bleeding assessment tools (BAT)

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14
Q

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

A

2 hrs

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15
Q

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

A

30 minutes

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16
Q

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.

A

5 minutes

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17
Q

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

A

5 mns

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18
Q

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.

A

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

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19
Q

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

A

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

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20
Q

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

A

19 gauge needle

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21
Q

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

A

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

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22
Q

the transferring of blood from syringe to tube is done using

A

19 gauge safety transfer unit; slowly inject through tube closure

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23
Q

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.

A

sodium citrate

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24
Q

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

A

Siliconized (plastic-coated) glass tubes

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25
Q

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

A

no po

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26
Q

content and percent of sodium citrate used

A

0.105 - 0.109 M (3.2%) sodium citrate

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27
Q

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

A

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

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28
Q

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

A

9:1 ratio

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29
Q

the collection ratio of 9:1 has what legends

A

9 parts whole blood to 1 part
anticoagulant

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30
Q

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

A

2.7

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31
Q

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

A

10.5 to 10.9 mM

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32
Q

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

A

55% or below

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33
Q

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

A

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

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34
Q

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

A

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

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35
Q

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

A

EDTA irreversibly chelates calcium ions

EDTA doesn’t preserve labile factors

inhibits thrombin-fibrinogen reaction

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36
Q

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

A

calcium chloride

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37
Q

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

A

complete blood count including PLATELET COUNT

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38
Q

________ (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.

A

Heparinized (green closure)

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39
Q

reason why we are not using heparin for hemostasis testing?

A

binds with anti-thrombin III

inhibits all coagulation reaction

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40
Q

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

A

platelet retention/glass bead retention test

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41
Q

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

A

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

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42
Q

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

A

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

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43
Q

anticoagulant in yellow closure

A

acid citrate dextrose (ACD)

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44
Q

dipotassium EDTA (k2EDTA ) is an anticoagulant in what closure

A

dipotassium EDTA (k2EDTA )

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45
Q

tubes suppress in vitro platelet or coagulation activation for specialty assay

A

Citrate theophylline adenosine dipyridamole (CTAD, blue closure)

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46
Q

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

A

platelet activation marker platelet factor 4 (PF4)

or

coagulation activation marker thrombin-antithrombin complex (TAT)

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47
Q

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

A

red-closure glass

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48
Q

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

A

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

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49
Q

this venipuncture procedure is Preferred over syringe method

A

evacuated tube system

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50
Q

this venipuncture procedure allows the Blood directly mixes with anticoagulant

A

evacuated tube system

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51
Q

ORDER OF DRAW

A

oRed top tube
oLight blue
oEDTA
oPlastic syringe

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52
Q

in Syringe Method

what is the use of first syringe

A

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

53
Q

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

A

collected for coagulation studies

54
Q

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

A

prevent contamination
maintains accurate result

55
Q

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

A

negative internal pressure

56
Q

why do we need to prevent having shortdraw in coagulation testing

A

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

57
Q

what should we do in short draw specimen

A

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

58
Q

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

A

negative internal

59
Q

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

A

90

60
Q

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

A

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

61
Q

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

true or false

A

true

62
Q

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

A

at least 3 times

63
Q

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

A

cocktail shaking

64
Q

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

A

stasis

65
Q

_________ 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.

A

Stasis

66
Q

collecting blood in vascular access device

Before blood is collected for hemostasis testing, the line must be
flushed with______ of saline,

A

5 mL

67
Q

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.

A

5 mL

68
Q

example of vascular access device

A

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

69
Q

site of capillary function

A

off center of the fingertip and perpendicular to the fingerprint lines

70
Q

what type of blood is ideal for capillary puncture coagulation test

A

free flowing blood

71
Q

Further, hemolysis interferes with _______ result

A

optical endpoint coagulometer

72
Q

LIPEMIC OR ICTERUS SAMPLE interfere with __ method

A

chromogenic substrate

73
Q

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

A

electro-mechanical detection method

74
Q

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

A

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

75
Q

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

A

factors V and VIII

76
Q

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

A

pH rise and results to falsely prolonged PT and PTT

77
Q

relationship of pH to bleeding

A

rise in pH increase PT and PTT

alkaline blood means bleeding

78
Q

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

A

15° C to 25° C

79
Q

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

A

24

80
Q

what pathway is related to PT?

A

PTEX

PT = EXTRINSIC PATHWAY (FIII and FVII)

81
Q

what pathway is related to PTT?

A

intrinsic and common pathway

82
Q

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.

A

4 hrs

83
Q

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
________

A

heparin

84
Q

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

A

15° C to 25° C

85
Q

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

A

1 hour

86
Q

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

A

plastic freezer tube

87
Q

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

A

no, glass stimulates the intrinsic coagulation pathway

88
Q

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

A

-20*C

89
Q

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

A

-70*C

90
Q

PT with no UFH

specimen stability

A

test within 24 hr maintain upright and sealed

91
Q

PTT with no UFH

specimen stability

A

test within 4 hr maintain upright and sealed

92
Q

PTT with monitoring UFH

A

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

93
Q

PT with monitoring UFH

A

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

94
Q

factor assays specemin stability

A

test within 4 ht maintain upright and sealed

95
Q

optical platelet aggregometry using PRP specimen stability

A

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

96
Q

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

true or false

A

true

97
Q

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

A

4

98
Q

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

A

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

99
Q

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

A

1:1

100
Q

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

A

Light-transmittance (optical) platelet aggregometers

101
Q

platelet poor plasma has how many platelets?

A

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

102
Q

centrifugation of PPP

A

10-15 mn, 2000 - 2500 rpm

103
Q

PPP is tested within

A

2 hrs

104
Q

refrigerated temp of PPP

A

no longer 4 hrs

105
Q

freezing temp of PPP

A

-20 to -70*C

106
Q

PPP is used in what studies

A

coagulation studies

107
Q

Platelet Rich Plasma (PRP) has how many PLTS

A

250 x 10 ^9 PLT/l

108
Q

CENTRIFUGATION of PRP

A

10-15 mns 60-100 rpm

109
Q

PRP is stored at what temp

A

room temp

110
Q

PRP is used in what studies

A

platelet studies

111
Q

How aspirin affects hemostasis testing?

A

inhibits cyclooxygenase

112
Q

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

A

7 days

113
Q

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

A

1 day

114
Q

how heprarin affects hemostasis testing

A

affects cyclooxygenase
inhibits most clotting factors

115
Q

antagonist of prothrombin group and vitamin K dependent clotting factors

A

warfarin/coumadin

116
Q

it prevents gamma carboxylation of vitamin K on clotting factors

A

warfarin/coumadin

117
Q

it alters blood vessels and induces hemolysis

A

penicillin

118
Q

most potent penicillin capable of affecting platelet function

A

carbenicillin

119
Q

it prematurely activates clotting process (extrinsic pathway )

A

tissue thromboplastin contamination

120
Q

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

A

tissue thromboplastin

121
Q

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

A

glass surfaces

122
Q

the factors that prematurely activates at ref temp 4*C

A

factor VII and Factor XI

123
Q

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

A

labile factors factor V and factor VIII

124
Q

how hemolysis affects sample and testing

A

releases tissue thromboplastin like substance that will activate clotting system

release ADP that causes platelet aggregation

125
Q

how tourniquet affect hemostasis testing

A

causes venous stasis

activates clotting factors

126
Q

increased pH effect to hemostasis testing

A

associated with loss of carbon dioxide that deteriorates clotting factors

sample must be unopened and tested within 6 hrs

127
Q

effect of polycythemia vera in hemostasis testing

A

increases hematocrit by >50%

prolongs clotting time test

128
Q

incomplete filling of tubes can result to ___

A

increased amount of citrate (prolonged)

HEMATOLOGY 2 (9 decks)

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