Question 1

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

Accepted Answer

The immediate correction suggests a factor deficiency, but the lack of correction after incubation indicates a time-dependent inhibitor, such as a factor VIII inhibitor.

Question 2

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

Accepted Answer

Preanalytical quality control procedures necessary when performing platelet aggregation studies include assessing patient medications before obtaining the specimen. Patients may be taking medications that affect platelet function, such as aspirin or other antiplatelet drugs, which can alter the results of the study. Obtaining the specimen after a 12-hour fast or performing a bleeding time test is not necessary for platelet aggregation studies. Collecting the specimen in a glass tube may also not be necessary as long as the anticoagulant and storage conditions meet the requirements for the specific test being performed.

Question 3

Which of the following instruments uses both electromechanical and optical density as a means of clot detection?
A) STArt 4 Coagulation system
B) BBL Fibrosystem
C) Trinity Biotech Coag-A-Mate XM
D) AMAX Destiny Plus

Accepted Answer

The AMAX Destiny Plus uses both electromechanical and optical methods for clot detection, providing versatility in coagulation testing.

Question 4

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

Accepted Answer

The ISTH guidelines for the diagnosis of lupus anticoagulant (LA)/antiphospholipid (aPL) include the demonstration of the presence of an inhibitor. This is because lupus anticoagulant is an antibody that interferes with normal phospholipid-dependent coagulation tests, leading to a prolonged clotting time in vitro, which indicates the presence of an inhibitor rather than a deficiency of clotting factors or abnormalities in PT (prothrombin time).

Question 5

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

Accepted Answer

Factor VIII deficiency primarily affects the intrinsic pathway, which would prolong APTT but not PT significantly. PT is more reflective of the extrinsic and common pathways, where factors V, II, and fibrinogen play critical roles.

Question 6

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

Accepted Answer

A fibrinolytic deficiency would result in decreased ability to break down clots, leading to an increased risk of clot formation. Therefore, the patient would be prone to increased clotting.

Question 7

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

Accepted Answer

Fibrinopeptides C and F are not markers of fibrin formation and fibrinolysis, but rather fragments produced during the cleavage of fibrinogen to fibrin. The other three options (B, C, and D) all measure activation of the hemostatic mechanism using markers of fibrin formation and fibrinolysis.

Question 8

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

Accepted Answer

Factor XIII is not directly involved in the coagulation pathway and therefore is not typically measured in the workup of prolonged PT and APTT. The other tests listed (D-dimer, liver function tests, fibrinogen) are routinely ordered in the workup of coagulation disorders.

Question 9

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

Accepted Answer

The answer of The anticoagulant of 3.2% sodium citrate is...

Question 10

A hemophilic A patient has a severe bleed and is being treated with Factor VIII concentrate. When testing his post infusion, 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

Accepted Answer

A lack of increase in Factor VIII level after infusion suggests the presence of a Factor VIII inhibitor, which is an antibody that neutralizes the therapeutic effects of Factor VIII concentrate. Lupus anticoagulant and improper drawing of the specimen would not affect the increase in Factor VIII level post-infusion. Factor IX inhibitor would not affect the response to Factor VIII concentrate.

Question 11

An analyzer is measuring a clot forming by the interaction of a stationary probe with a moving probe in a continuous motion. Suddenly the moving probe stops, and a clot is seen. Name the analyzer.
A) Diagnostica Stago
B) MDA 180
C) Trinity Biotech AMAX Destiny Plus
D) BBL Fibrometer

Accepted Answer

The BBL Fibrometer measures clot formation using a moving probe and a stationary probe in a continuous motion. When the moving probe stops, a clot can form and be measured by the analyzer. The other three analyzers listed do not utilize the same method of clot formation measurement.

Question 12

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

Accepted Answer

Reptilase time is a test that is highly sensitive for heparin contamination. It is not affected by heparin and will differentiate between heparin-induced prolongation of the APTT and a true coagulation factor deficiency. The other options are not as specific for evaluating heparin contamination.

Question 13

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

Accepted Answer

The answer of Laboratory testing for von Willebrand factor contains...

Question 14

A patient is screened positive for APCR. What does this mean? A) The patient is at risk for hemorrhage. B) The patient has a high probability of factor V_Leiden mutation. C) The patient is on warfarin. D) The patient is on heparin.

Accepted Answer

APCR (Activated Protein C Resistance) is a condition where the person's blood is resistant to the anticoagulant effects of protein C, resulting in an increased risk of developing blood clots. The most common cause of APCR is the presence of Factor V Leiden mutation. Therefore, a positive APCR screening indicates a high probability of having Factor V Leiden mutation.

Question 15

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

Accepted Answer

Functional measurement of PC, PS, and ATIII is the preferred test for evaluating thrombotic disorders as it measures the activity of these proteins rather than just their presence. Antigenic measurement only confirms the presence of the protein but does not provide information on its function. Platelet function tests are useful for evaluating bleeding disorders, not thrombotic disorders. Lupus anticoagulant testing is important in evaluating antiphospholipid syndrome, but it is not specific to thrombotic disorders.

Question 16

Choose the correct statement regarding chromogenic analysis in hemostasis testing from the following choices.
A) Chromogenic analysis depends on the selected analyte's ability to cleave a chromophore.
B) Chromogenic analysis is not subject to preanalytical problems because of its mechanism of clot detection.
C) There is no difference between chromogenic analysis and electromechanical detection.
D) Chromogenic analysis depends on the optical detection of ball movement through a steel tube as a clot forms.

Accepted Answer

Chromogenic analysis relies on the ability of an analyte to cleave a chromophore, which then leads to a change in color that can be detected optically. Option B is incorrect because chromogenic analysis may be subject to preanalytical problems such as interference from lipemia or hemolysis. Option C is incorrect because chromogenic analysis and electromechanical detection are different methods of clot detection. Option D describes the mechanical clot detection method, not chromogenic analysis.

Question 17

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

Accepted Answer

The platelet aggregation defect seen in the patient is consistent with RIPA defect, which is a characteristic finding in von Willebrand's disease. Adding normal plasma to the patient's PRP corrected the defect, which indicates a deficiency or dysfunction of vWF in the patient's plasma. Sticky platelet syndrome is a rare disorder characterized by platelet hyperaggregability, but it is not associated with RIPA defect. Bernard-Soulier syndrome is associated with a defect in the glycoprotein Ib-IX-V receptor, and afibrinogenemia is a rare bleeding disorder characterized by the absence of fibrinogen. Neither of these disorders is associated with RIPA defect.

Question 18

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

Accepted Answer

The prolonged APTT and BT and abnormal aggregation on the PFA suggest a possible factor deficiencies or von Willebrand's disease, which are both related to the intrinsic pathway. Prothrombin time, on the other hand, assesses the extrinsic pathway and would not help define the disorder. Therefore, it is not a useful test in this scenario. The other three tests, (A) von Willebrand's factor activity, (B) von Willebrand's factor antigen, and (C) Factor VIII assay, all assess the intrinsic pathway and are more appropriate for further evaluation of the patient's bleeding disorder.

Question 19

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

Accepted Answer

The Bethesda titer is the most appropriate reflex test when Factor VIII:C assay is <1%, indicating severe Hemophilia A. This test quantifies the inhibitor level against Factor VIII, crucial for managing and treating the condition.

Question 20

Siemens BCS coagulation analyzers use what method of optical clot detection?
A) Electromechanical
B) Chromogenic
C) Turbidometric
D) Mechanical

Accepted Answer

Siemens BCS coagulation analyzers use the turbidometric method of optical clot detection, which measures changes in light scattering due to clot formation.

Quiz 36: Hemostasis: Laboratory Testing and Instrumentation

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?

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

Which of the following instruments uses both electromechanical and optical density as a means of clot detection?

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 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 patient with a fibrinolytic deficiency would:

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

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

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

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

An analyzer is measuring a clot forming by the interaction of a stationary probe with a moving probe in a continuous motion. Suddenly the moving probe stops, and a clot is seen. Name the analyzer.

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

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

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

Choose the correct statement regarding chromogenic analysis in hemostasis testing from the following choices.

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 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?

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%

Siemens BCS coagulation analyzers use what method of optical clot detection?