Question 1

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

Accepted Answer

Increased levels of fibrin degradation products can interfere with fibrin polymerization, leading to a prolonged thrombin time.

Question 2

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

Accepted Answer

C

Question 3

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

Accepted Answer

Activated partial thromboplastin time requires calcium chloride, as it is needed to activate the clotting cascade, and partial thromboplastin reagent, which contains phospholipids and activates coagulation factors. Potassium chloride and thromboplastin are not necessary for this test.

Question 4

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

Accepted Answer

Tissue factor and anticoagulant carryover are both contaminants that can interfere with coagulation testing. Sodium citrate and heparin anticoagulant are actually necessary for proper coagulation testing, and air and high hematocrit are not typically considered contaminants for this type of testing.

Question 5

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.

Accepted Answer

A prolonged APTT with a normal PT indicates a deficiency or defect in the intrinsic pathway. This could be due to a congenital factor deficiency, acquired inhibitor or other factors that affect the pathway. The other options, such as being on Coumadin, having an inhibitor to a factor in the extrinsic pathway, or having a vitamin K deficiency, would not solely affect the APTT without also affecting the PT.

Question 6

POC coagulation testing is beneficial in all of the following situations except:
A) Rapid therapeutic decision making during liver transplant surgery
B) Out-patient warfarin monitoring on stabilized patients
C) Confirmation testing for VWD following a prolonged APTT result
D) Rapid screening of platelet function for patients on aspirin therapy

Accepted Answer

POC coagulation testing is not typically used for confirmation testing for von Willebrand Disease (VWD) following a prolonged APTT result, as this requires more specific laboratory tests.

Question 7

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

Accepted Answer

Recombinant factor VIIa (rFVIIa) is used to increase the levels of factor VIIa in the blood, which is involved in the initiation of the coagulation cascade. By increasing the levels of factor VIIa, rFVIIa helps to promote clot formation, thereby shortening the prothrombin time (PT), which is a measure of the blood's ability to clot.

Question 8

Choose the correct statement regarding proper specimen collection for coagulation testing from the following choices:
A) The tube needed for coagulation testing should always 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 never be used when drawing coagulation tubes

Accepted Answer

When drawing blood from a catheter, care must be taken to avoid heparin contamination. Heparin can interfere with coagulation testing and lead to inaccurate results. It is important to discard the first few mLs of blood when drawing from a catheter to avoid heparin contamination. Option A is incorrect because coagulation tubes should be drawn after other blood tubes. Option B is incorrect because the sodium citrate tube should be filled to the stated volume regardless of the patient's hematocrit level. Option D is incorrect because butterfly needles can be used for coagulation testing as long as they are the appropriate gauge and length.

Question 9

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

Accepted Answer

The patient's presentation of a prolonged PT with normal APTT and TT suggests a deficiency in the extrinsic pathway, which points to Factor VII deficiency. Factor VII is unique to the extrinsic pathway, which is assessed by the PT test.

Question 10

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

Accepted Answer

Room temperature, depth, location and direction of the incision; movement of the arm, and laboratician experience are all variables of the bleeding time method. A standardized method eliminates these variables to provide consistent and accurate results. The other options (A, B, D) represent factors that may affect platelet function and/or count, but they are not variables specific to the bleeding time method itself.

Question 11

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

Accepted Answer

The purpose of the INR is to standardize the patient's PT worldwide, minimize variability of results between laboratories, and minimize variability of results between lots of thromboplastin. However, it is not designed to correlate the PT with the aPTT.

Question 12

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

Accepted Answer

The aPTT test measures the time it takes for a clot to form in plasma after adding an activator and calcium. The reagent used in the test is usually a partial thromboplastin combined with calcium. This reagent activates the intrinsic coagulation pathway, leading to the formation of a fibrin clot. Choice A is incorrect as thromboplastin is not used in the aPTT test. Choice C is incorrect as it mentions thrombin and fibrinogen, which are part of the extrinsic pathway and not used in the aPTT test. Choice D is also incorrect as it mentions normal pooled plasma and thrombin, which is used in the prothrombin time (PT) test and not the aPTT test.

Question 13

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

Accepted Answer

Flushing the line with saline and discarding the first 5 ml of blood helps to prevent contamination and ensures that the sample collected is accurate.

Question 14

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

Accepted Answer

Bleeding time is the only test listed that specifically assesses platelet function in vivo (in the living body). Prothrombin time and activated partial thromboplastin time are laboratory tests that evaluate coagulation factors, not platelet function. Platelet aggregation studies are in vitro tests that involve adding platelet agonists to a blood sample to see how well the platelets clump together, but this does not necessarily reflect platelet function in vivo.

Question 15

Prothrombin time measures the clotting factors in the:
A) Intrinsic pathway
B) Formation of fibrin
C) Extrinsic pathway
D) Fibrinolytic pathway

Accepted Answer

Prothrombin time measures the extrinsic pathway of the coagulation cascade, which is activated by tissue factor (factor III). This pathway ultimately leads to the conversion of prothrombin to thrombin, which then converts fibrinogen to fibrin, forming a blood clot.

Question 16

Interpret the following results. • PT = 32 sec
• APTT = 92 sec
• TT = >100 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.

Accepted Answer

The prolonged APTT and TT suggest an inhibition of the intrinsic and common coagulation pathways, which is consistent with heparin contamination. The PT is not significantly prolonged, which rules out liver disease or Coumadin therapy as the cause. DIC may also cause abnormal coagulation results, but typically results in a prolonged PT and APTT as well as low fibrinogen and platelet counts.

Question 17

Which of the following tests can be used to monitor Coumadin therapy?
A) PT-INR
B) Factor assays
C) APTT
D) Reptilase time

Accepted Answer

PT-INR is the appropriate test to monitor Coumadin therapy.

Question 18

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

Accepted Answer

Normal pooled plasma contains 100% of all the factors needed to achieve a clot, making it the ideal diluent for a mixing study. This ensures that any clotting factor deficiencies in the patient sample are not due to a lack of coagulation factors in the diluent.

Question 19

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

Accepted Answer

Severe liver disease can lead to impaired synthesis of clotting factors, which are mostly produced in the liver. This can result in prolonged Prothrombin Time (PT) and Thrombin Time (TT), and increased Fibrin Degradation Products (FDP) due to secondary fibrinolysis.

Question 20

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

Accepted Answer

The target goal of the ISI value in commercial reagents is to obtain a reagent that has an ISI of 1.0 or close to it. This allows for accurate and consistent results across different laboratories and manufacturers.

Quiz 36: Hemostasis: Laboratory Testing and Instrumentation

Thrombin time is prolonged with a patient who has:

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

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

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

POC coagulation testing is beneficial in all of the following situations except:

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

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

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

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?

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

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?

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

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

Prothrombin time measures the clotting factors in the:

Interpret the following results. • PT = 32 sec • APTT = 92 sec • TT = >100 sec. What is the most likely reason for these aberrant results?

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

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

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

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