12 Questions
What is the most sensitive index of heparin therapy and disseminated intravascular coagulation (DIC)?
Thrombin time
Which pathway(s) does the activated partial thromboplastin time (aPTT) screen for abnormalities in?
Extrinsic and intrinsic pathways
Which laboratory test is most commonly used to monitor oral anticoagulant therapy?
Prothrombin time (PT)
How can it be determined if a patient has an inhibitor instead of a factor deficiency?
Mixing studies will remain prolonged
What does the bleeding time test measure?
Platelet adhesion and aggregation on locally injured vascular subendothelium
Which test is the basic principle of the fibrinogen test most similar to?
Clauss assay
What is the name of the reagent used for performing the prothrombin time test?
Thromboplastin and calcium
Which coagulation disorder is often characterized by decreased aggregation with ristocetin?
Von Willebrand's disease
Which of the following tests are usually abnormal in hemophilia A?
aPTT and factor VIII level
Elevated fibrin split products (FSP's) can be seen in all of the following EXCEPT:
Factor VIII deficiency
What is the name of the coagulation test that measures the time it takes for blood to clot?
Bleeding time
Which of the following is NOT a coagulation test?
Complete blood count
Study Notes
Coagulation Studies
- The most sensitive index of heparin therapy and DIC is the thrombin time.
- Activated partial thromboplastin time (aPTT) screens for abnormalities in intrinsic and common pathways.
- Prothrombin time (PT) is the most common laboratory test to monitor oral anticoagulant therapy.
Bleeding Time
- Bleeding time test measures platelet adhesion and aggregation on locally injured vascular subendothelium.
- Bleeding time is not affected by coagulation factor cascade or platelet quantity and quality.
Fibrinogen Test
- The basic principle of the fibrinogen test is similar to the thrombin time test.
Mixing Studies
- Mixing studies can help distinguish between a factor deficiency and an inhibitor.
- If PT and aPTT are corrected, it suggests a factor deficiency, whereas if they remain prolonged, it suggests an inhibitor.
Ristocetin-Induced Platelet Aggregation
- Decreased aggregation with ristocetin is often found in patients with von Willebrand's disease.
Hemophilia A
- In hemophilia A, aPTT, factor VIII level, and vWF:Ag are usually abnormal.
Fibrin Split Products (FSP's)
- Fibrin split products (FSP's) can be elevated in sepsis, pulmonary embolism, and extreme exercise, but not in factor VIII deficiency.
This quiz tests your knowledge on blood coagulation, anticoagulant therapy, and laboratory tests used to monitor them. Questions cover topics such as heparin therapy, DIC, and oral anticoagulant therapy.
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