Approach To Thrombosis

Question 1

What are the social correlates related to thrombotic disorders?

Answer 1

Traffic, road users, organization, regulatory mechanisms

These factors can influence the prevalence and management of thrombotic disorders.

Question 2

What is the main goal of haemostasis?

Answer 2

To stop bleeding and to do so only at the site of injury

This involves a balance between pro-coagulant and anticoagulant mechanisms.

Question 3

What does Virchow’s triad consist of?

Answer 3

Three components: stasis, hypercoagulability, endothelial injury

These factors contribute to the risk of thrombosis.

Question 4

What are the two main processes of haemostasis?

Answer 4

• Primary haemostasis
• Secondary haemostasis

Primary involves vasoconstriction and platelet plug formation; secondary involves coagulation factors.

Question 5

What is the role of platelets in primary haemostasis?

Answer 5

Formation of a platelet plug

This is the first physiological response to blood vessel injury.

Question 6

What is the purpose of secondary haemostasis?

Answer 6

To stabilize and reinforce the weak platelet plug and convert fibrinogen to fibrin

This prevents further blood loss from the injury site.

Question 7

Name two key components involved in the coagulation pathways.

Answer 7

• Tissue factor (TF)
• Calcium

These components are essential for the activation of coagulation factors.

Question 8

What are the main steps in the cell-based model of haemostasis?

Answer 8

• Initiation
• Amplification
• Propagation

These steps describe how coagulation factors are activated to form fibrin.

Question 9

What are promoters of fibrinolysis?

Answer 9

• Plasmin
• Tissue plasminogen activator (tPA)

These substances help dissolve clots and restore blood flow.

Question 10

What are inhibitors of fibrinolysis?

Answer 10

• Antiplasmin
• Plasminogen activator inhibitor-1 (PAI-1)

These substances prevent excessive clot breakdown.

Question 11

What factors can contribute to acquired risk factors for thrombosis?

Answer 11

• Age
• Pregnancy
• Trauma
• Surgery
• Immobility
• Malignancy

These factors can increase the risk of thrombotic events.

Question 12

What is thrombotic thrombocytopenic purpura (TTP)?

Answer 12

A condition characterized by renal failure, hemolytic anemia, and thrombocytopenia

Treatment includes fresh frozen plasma and plasma exchange.

Question 13

What is a common inherited thrombophilia condition?

Answer 13

Factor V Leiden

This condition increases the risk of thrombosis and is prevalent in Caucasian populations.

Question 14

Fill in the blank: The process of _______ stabilizes and reinforces the clot formed during primary haemostasis.

Answer 14

Secondary haemostasis

This involves the conversion of fibrinogen to fibrin.

Question 15

True or False: Antithrombin deficiency is an autosomal dominant condition.

Answer 15

True

This condition significantly increases the risk of thrombosis.

Question 16

What are the two physiological responses involved in primary haemostasis?

Answer 16

• Local vasoconstriction
• Platelet plug formation

These responses occur immediately after vascular injury.

Question 17

What is the function of the vascular endothelium in haemostasis?

Answer 17

• Anticoagulant properties
• Procoagulant properties

It regulates the balance between bleeding and clotting.

Question 18

What does a thrombophilia screen test for?

Answer 18

Deficiencies or abnormalities in coagulation factors

This helps identify the underlying causes of thrombotic events.

Question 19

What are the three main components of Virchow’s triad?

Answer 19

• Stasis
• Endothelial injury
• Hypercoagulability

These factors contribute to thrombosis risk.

Question 20

What is Factor V Leiden?

Answer 20

Commonest genetic risk factor for thrombosis, present in 5% of Caucasian population, rare in black and Asian populations. Causes activated protein C resistance, increasing risk by 7%.

Factor V Leiden is a mutation that affects the clotting process, leading to increased risk of venous thromboembolism.

Question 21

What is the Prothrombin 20210 mutation?

Answer 21

G20210A mutation on chromosome 11, increases risk of thrombosis by 3%.

This mutation leads to elevated levels of prothrombin, a clotting factor, which can contribute to venous clots.

Question 22

What is the prevalence of Protein C deficiency?

Answer 22

Prevalence is 0.2-0.3%, inherited in an autosomal dominant manner, located on chromosome 2, and increases thrombosis risk by 10-15%.

Protein C plays a crucial role in regulating blood coagulation.

Question 23

What is Protein S deficiency?

Answer 23

An autosomal dominant condition located on chromosome 3, liver and vitamin K dependent, increasing thrombosis risk by 2%.

Protein S is a cofactor for Protein C, and its deficiency can lead to increased clot formation.

Question 24

What are common investigations for thrombosis diagnosis?

Answer 24

Doppler ultrasound scan, venogram.

These imaging techniques help visualize clots in veins, particularly in the legs.

Question 25

What is included in a thrombophilia screen?

Answer 25

Lupus anticoagulant, CD55/59, Protein C/S/Antithrombin, Factor V Leiden, Prothrombin 20210. ## Footnote This screen helps identify inherited or acquired conditions that predispose to thromboembolism.

Question 26

What is the purpose of the Wells Criteria for DVT?

Answer 26

To assess the clinical probability of DVT based on specific features and risk factors. ## Footnote The Wells Criteria assigns points for various clinical features to categorize patients into high, moderate, or low probability of DVT.

Question 27

What clinical feature scores 1 point in the Wells Criteria for DVT?

Answer 27

Active cancer, paralysis or paresis, recent immobilization of lower extremities, localized tenderness along deep veins, entire leg swollen, calf swelling by >3 cm, pitting edema, collateral superficial veins. ## Footnote Each feature contributes to the overall score used to determine the likelihood of DVT.

Question 28

What is the indication for anticoagulation in thrombosis treatment?

Answer 28

To prevent progression of thrombosis and reduce the risk of embolism. ## Footnote Anticoagulation therapy is crucial in managing venous thromboembolism, including DVT and PE.

Question 29

What are the side effects of Warfarin?

Answer 29

Hemorrhagic complications (intracerebral, GIT, hematuria, epistaxis), skin necrosis, purple toe, allergic reactions, hepatic dysfunction, teratogenic effects. ## Footnote Warfarin requires careful monitoring due to its risk of bleeding and other side effects.

Question 30

What is the half-life of S-warfarin?

Answer 30

45 hours. ## Footnote S-warfarin is more potent than R-warfarin and is primarily responsible for anticoagulant activity.

Question 31

What is the primary mechanism of action for Heparin?

Answer 31

Inhibits thrombin (FIIa) and factor Xa (FXa) in the coagulation cascade. ## Footnote Heparin works by enhancing the activity of antithrombin, leading to decreased thrombin formation.

Question 32

What is the difference between high molecular weight heparin (HMWH) and low molecular weight heparin (LMWH)?

Answer 32

HMWH has a variable bioavailability and requires monitoring with APTT; LMWH has predictable bioavailability and usually does not require monitoring. ## Footnote The choice between HMWH and LMWH depends on patient factors and treatment goals.

Question 33

What are the risk factors for hemorrhagic complications in patients on Warfarin?

Answer 33

Old age, poor anticoagulant control, prolonged treatment duration, and specific sites of bleeding. ## Footnote Identifying these risk factors can help mitigate the risk of severe bleeding events.

Question 34

What is the target INR for DVT treatment with Warfarin?

Answer 34

2-3. ## Footnote Maintaining the INR within this range is essential to balance the risk of thrombosis and bleeding.

Question 35

What should be done if a patient's INR is above the therapeutic range?

Answer 35

Consider holding the dose, administering vitamin K, or fresh frozen plasma for rapid reversal. ## Footnote The strategy for reversal depends on the level of INR and the urgency of the situation.