Deck 36: Hemostasis: Laboratory Testing and Instrumentation

Question 1

If blood is collected through an indwelling catheter,care must be taken to:

A)Prevent the citrate contamination of the line
B)Flush the line with saline and discard the first 5 ml of blood
C)Draw the sample quickly to prevent clotting
D)Flush the line with sterile water

Answer 1

Flush the line with saline and discard the first 5 ml of blood

Question 2

Prothrombin time measures the clotting factors in the:

A)Intrinsic pathway
B)Formation of fibrin
C)Extrinsic pathway
D)Fibrinolytic pathway

Answer 2

Extrinsic pathway

Question 3

Proper specimen collection for coagulation testing must be performed to eliminate contamination of substances that will interfere with the test results.Which of the following are considered contaminants for coagulation testing?

A)Sodium citrate and heparin anticoagulant
B)Tissue factor and anticoagulant carryover
C)Air and tissue factor
D)High hematocrit and anticoagulant carryover

Answer 3

Tissue factor and anticoagulant carryover

Question 4

The international normalized ratio (INR)is used to standardize the wide variations in the reagent of prothrombin testing.What is the goal of creating the ISI value?

A)Reduce the lot-to-lot variability
B)Correlate one manufacturer with another
C)Obtain a reagent that has an ISI of 1.0 or close to it
D)Reduce the use of anticoagulant therapy

Question 5

Which of the following tests can be used to monitor Coumadin therapy?

A)PT-INR
B)Factor assays
C)APTT
D)Reptilase time

Question 6

Choose the correct statement regarding proper specimen collection for coagulation testing from the following choices:

A)The tube needed for coagulation testing should be the first tube drawn.
B)It is acceptable to fill the sodium citrate tube halfway in a polycythemic patient for coagulation testing.
C)When drawing blood from a catheter,care must be taken to avoid heparin contamination.
D)Butterfly needles should not be used when drawing coagulation tubes.

Question 7

A patient has a prolonged APTT with a normal PT.There were no errors in specimen collection.What does this mean for the patient?

A)There could be a defect in the intrinsic pathway.
B)The patient is on Coumadin.
C)The patient has developed an inhibitor to a factor in the extrinsic pathway.
D)The patient has a vitamin K deficiency.

Question 8

Thrombin time is prolonged with a patient who has:

A)Increased levels of fibrin degradation products
B)Increased levels of fibrinogen
C)Factor deficiencies
D)Presence of lupus anticoagulants

Question 9

Each of the following is the purpose of the INR except:

A)To standardize the patient's PT worldwide
B)To minimize variability of results between laboratories
C)To minimize variability of results between lots of thromboplastin
D)To correlate the PT with the aPTT

Question 10

Normal pooled plasma is used as the diluent in a mixing study because it:

A)Minimizes SERPIN activity
B)Contains 100% of all the factors needed to achieve a clot
C)Minimizes the effects of sodium citrate on the sample
D)Neutralizes any residual platelets left in the sample after centrifugation

Question 11

Calculate the INR using the following data: Patient PT = 14.8 sec;normal PT sec = 12.2 sec;ISI = 1.3.

A)2.29
B)2.40
C)1.29
D)1.40

Question 12

A patient has severe liver disease.What test results would you expect?

A)Prolonged PT,TT,increased FDP
B)Prolonged APTT and normal TT
C)Decreased fibrinogen and Normal TT
D)Prolonged bleeding time and Normal APTT

Question 13

Interpret the following results. -PT = 32 sec
-APTT = 92 sec
-TT = 20 sec.
What is the most likely reason for these aberrant results?

A)The patient is in DIC.
B)There is heparin contamination of the sample.
C)The patient is taking Coumadin.
D)The patient has liver disease.

Question 14

Based on the following data,what is the patient's most likely factor deficiency?
PT Prolonged
APTT Normal
TT Normal

A)F-II
B)F-X
C)F-IX
D)F-VII

Question 15

A citrated blood sample is tested with the following results: -PT = 60.0 seconds
-APTT = 100.0 seconds
Pending further testing,the most probable reason for these results is not:

A)Factor VIII deficiency
B)Factor V deficiency
C)Factor II deficiency
D)Fibrinogen deficiency

Question 16

What effect does the administration of recombinant factor VIIa concentrate have on the PT levels?

A)Prolongs the PT by having an absence of vitamin K
B)Shortens the PT by having an absence of factor VII
C)Shortens the PT by having increased levels of rFVIIa
D)Prolongs the PT by having thromboplastin using a recombinant TF

Question 17

Which of the following tests is used to assess platelet function in vivo?

A)Prothrombin time
B)Activated partial thromboplastin time
C)Bleeding time
D)Platelet aggregation studies

Question 18

The aPTT is the most common procedure used to monitor the unfractionated heparin therapy.Which of the reagents used in the test provides the activation of the formation of the fibrin clot?

A)Thromboplastin/calcium mixture
B)Activated partial thromboplastin and calcium
C)Thrombin and fibrinogen
D)Normal pooled plasma and thrombin

Question 19

The platelet function analyzer standardized the bleeding time method by eliminating the variables of the method.Which of the following represents the variables of bleeding time?

A)Dependence on the presence of calcium
B)Ingestion of aspirin
C)Room temperature,depth,location and direction of the incision;movement of the arm,and laboratician experience
D)Abnormal platelet count

Question 20

Which of the following is needed to perform an activated partial thromboplastin time?

A)Potassium chloride and partial thromboplastin reagent
B)Partial thromboplastin reagent and calcium chloride
C)Thromboplastin and potassium chloride
D)Thromboplastin and calcium chloride

Question 21

A patient is screened positive for APCR.What does this mean?

A)The patient is at risk for hemorrhage.
B)The patient has a factor VLₑᵢdₑn mutation.
C)The patient is at risk for thrombosis.
D)The patient is on heparin.

Question 22

A patient with a fibrinolytic deficiency would:

A)Be prone to increased lysis
B)Have increased levels of plasminogen
C)Have abnormal screening tests (PT and APTT)
D)Be prone to increased clotting

Question 23

In testing for thrombotic disorders,the ideal test would be:

A)Antigenic measurement of PC,PS,ATIII
B)Functional measurement of PC,PS,ATIII
C)Platelet function test
D)Lupus anticoagulant

Question 24

A hemophilic A patient has a severe bleed and is being treated with Factor VIII concentrate.When testing his postinfusion,the factor VIII level does not increase.The problem could be:

A)Lupus anticoagulant
B)Improper drawing of the specimen
C)Factor VIII inhibitor
D)Factor IX inhibitor

Question 25

What preanalytical quality control procedures are necessary when performing platelet aggregation studies?

A)Assess patient medications before obtaining specimen
B)Obtain specimen after a 12-hour fast
C)Perform a bleeding time before testing
D)Collect the specimen in a glass tube

Question 26

The results of platelet-rich plasma (PRP)in the aggregation studies of a patient's blood were typical of ristocetin-induced platelet agglutination (RIPA)defect.The RIPA defect was corrected by adding normal plasma to the patient's PRP.In what disease is this seen?

A)Sticky platelet syndrome
B)Bernard-Soulier syndrome
C)Afibrinogenemia
D)von Willebrand's disease

Question 27

Explain the clinical significance of a prolonged time with each of the following:
a.Bleeding time
b.Prothrombin time
c.Activated partial thromboplastin time
d.Thrombin time

Question 28

Explain the effects of the following on coagulation testing:
a.Clotted sample
b.Ratio of blood to anticoagulant < 9:1
c.Patient hematocrit >55%
d.>1-hour difference between specimen collection and analysis

Question 29

Give the results (prolonged or normal)for the bleeding time,prothrombin time,activated partial thromboplastin time,and thrombin time for a patient on prolonged anticoagulant therapy.

Question 30

Which of the following is the most appropriate reflex test based on the following laboratory data?
PT: normal
APTT: prolonged
Factor VIII: C assay: <1%

A)DRVVT
B)Bethesda titer
C)Factor IX assay
D)Mixing studies

Question 31

A patient has prolonged PT and APTT.Which of the following tests would not be warranted to follow up these findings?

A)Factor XIII assay
B)D-dimer
C)Liver function tests
D)Fibrinogen

Question 32

The anticoagulant of 3.2% sodium citrate is preferred over 3.8% because:

A)It does not require an adjusted redraw on patients with high hematocrits.
B)The 3.8% sodium citrate tubes are no longer manufactured.
C)The 3.2% sodium citrate has more success with minimizing in vitro platelet activation.
D)It is more likely to prevent clotting with difficult draws.

Question 33

Laboratory screening test results strongly suggest heparin contamination.Which of the following tests would help assess this finding?

A)DRVVT
B)Reptilase time
C)APTT
D)AT III activity

Question 34

An outpatient has an INR of 6.5.This patient's previous test at the same facility had results in the therapeutic range of 2-3 on long-term anticoagulant therapy.The appropriate next step for the laboratory professional would be to:

A)Retest the patient sample
B)Recollect the specimen
C)Report the result
D)Notify the hematology supervisor

Question 35

A patient's laboratory coagulation test results in an immediate correction of the PT and aPTT after mixing studies and no correction after performing the PT and aPTT after a 2-hour incubation at 37°C.What is the possible deficiency or inhibitor?

A)Factor deficiency
B)Lupuslike anticoagulant
C)F-VIII inhibitor
D)F-V loss

Question 36

According to the International Society on Thrombosis (ISTH),the guidelines for diagnostic criteria for LA/aPL include the demonstration of which of the following?

A)Normal phospholipid-dependent coagulation reaction
B)Absence of a clotting factor
C)Presence of an inhibitor
D)Abnormal PT

Question 37

Laboratory testing for von Willebrand factor contains variables that can result in difficulty in diagnosing the disease.Which of the following factors is identified as a variable that can contribute to this difficulty?

A)Abnormal screening results
B)Difficulty in obtaining the specimen
C)Age of patient
D)Standardization of the reference plasma

Question 38

Which of the following tests does not measure activation of the hemostatic mechanism using markers of fibrin formation and fibrinolysis?

A)Fibrinopeptide C and fibrinopeptide F
B) Thrombin-antithrombin (TAT)complex
C) Prothrombin activation fragment F1 + 2
D)Plasmin-antiplasmin (PAP)complex

Question 39

List the tests that are commonly utilized in the workup of the following:
a.von Willebrand's disease
b.Hemophilia A
c.Factor VIII inhibitor
d.Bernard-Soulier syndrome
e.TTP

Question 40

A patient is admitted with prolonged epistaxis and prolonged bleeding from a recent tooth extraction.Initial screening workup reports prolonged APTT and BT,and abnormal aggregation on the PFA.Which of the following tests would not help define the disorder?

A)von Willebrand's factor activity
B)von Willebrand's factor antigen
C)Factor VIII assay
D)Prothrombin time

Question 41

Justify the need for a molecular marker test in the workup of a hemostatic problem.