Question 1

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

Accepted Answer

The RIPA defect, or ristocetin-induced platelet agglutination defect, is a characteristic feature of von Willebrand's disease. The correction of the defect by adding normal plasma also supports this diagnosis as von Willebrand factor is a protein found in plasma that is necessary for platelet function. Sticky platelet syndrome, Bernard-Soulier syndrome, and afibrinogenemia have different underlying mechanisms and would not be expected to show a correction of the RIPA defect by adding normal plasma.

Question 2

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

Accepted Answer

The answer of List the tests that are commonly utilized...

Question 3

An outpatient has an INR of 6.5.Previous testing at the same facility had results in the normal range of 2-3 for this patient on long-term anticoagulant therapy.The appropriate next step for the laboratorian would be:

Accepted Answer

The first step should be to retest the patient sample to confirm the accuracy of the INR result before taking further actions.

Question 4

Proper collection and processing of coagulation specimens is necessary for optimum results.What should be avoided when processing the sodium citrated specimens for testing?

Accepted Answer

Clotting of the specimen and underfilling of the tube should be avoided as they can lead to inaccurate coagulation test results. Clotting can consume clotting factors, and underfilling can alter the blood-to-anticoagulant ratio.

Question 5

A hemophilic patient (Hemophilia A) 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:

Accepted Answer

The lack of increase in factor VIII level after infusion suggests the presence of a factor VIII inhibitor in the patient's blood. This is a common complication of treatment in hemophilic patients, as their immune systems can develop antibodies against the infused factor VIII concentrate. This inhibitor neutralizes the factor VIII and prevents its function, resulting in ineffective treatment of bleeding episodes. Lupus anticoagulant or improper drawing of the specimen would not affect the factor VIII level in this context, and the presence of a factor IX inhibitor is not relevant in Hemophilia A patients who lack this factor.

Question 6

What preanalytical quality control prospect is necessary when performing platelet aggregation studies?

Accepted Answer

It is important to assess patient medications before obtaining a specimen for platelet aggregation studies as certain medications can affect platelet function and potentially alter the results. This allows for proper interpretation of results and helps prevent false positives or negatives. A 12 hour fast (B) and bleeding time (C) are not necessary for platelet aggregation studies, and collecting the specimen in a glass tube (D) is not recommended as it can activate platelets and alter results.

Question 7

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

Accepted Answer

APCR stands for Activated Protein C Resistance. It means that the patient has a genetic mutation (most commonly Factor V Leiden mutation) that leads to a decreased response to activated protein C, which is an anticoagulant protein in the body. This puts the patient at a higher risk for developing thrombosis (blood clots) in veins and arteries, such as deep vein thrombosis or pulmonary embolism. However, it does not necessarily mean that the patient will develop thrombosis, as other risk factors also play a role. The patient may need anticoagulant therapy or other preventive measures to reduce their risk of developing thrombosis.

Question 8

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

Accepted Answer

The answer of Which of the following tests does not...

Question 9

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)Greater than 1-hour difference between specimen collection and analysis

Accepted Answer

The answer of Explain the effects of the following on...

Question 10

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

Accepted Answer

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

Question 11

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.

Accepted Answer

The answer of Explain the clinical significance of a prolonged...

Question 12

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

Accepted Answer

The answer of Justify the need for molecular marker testing...

Question 13

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.

Accepted Answer

The answer of Give the results (prolonged or normal) for...

Question 14

A patient with a fibrinolytic deficiency would:

Accepted Answer

A fibrinolytic deficiency means that the patient would have decreased ability to dissolve blood clots and therefore would be prone to increased clotting.

Question 15

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 16

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

Accepted Answer

Functional measurement of Protein C (PC), Protein S (PS), and Antithrombin III (ATIII) is ideal for testing thrombotic disorders as it assesses the activity of these anticoagulant proteins, which is crucial for identifying deficiencies that could lead to thrombosis.

Question 17

A patient's laboratory coagulation testing 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?

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 18

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

Accepted Answer

The ISTH guidelines for diagnosing lupus anticoagulant (LA) or antiphospholipid antibodies (aPL) include demonstrating the presence of an inhibitor that interferes with phospholipid-dependent coagulation tests.

Question 19

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

Accepted Answer

The laboratory data suggests a deficiency or inhibitor of Factor VIII, as indicated by the prolonged APTT and very low Factor VIII:C assay. The Bethesda titer is used to quantify inhibitors against Factor VIII, making it the most appropriate reflex test in this scenario.

Quiz 39: Laboratory Testing in Coagulation

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

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