Clinical Haemostasis and Thrombosis

Question 1

What clinical feature is common to all bleeding disorders?

Answer 1

Easy bruising

Question 2

What constitutes the unstable platelet plug?

Answer 2

Exposed collagen - von Willebrand factor - platelets

Question 3

A disease of primary haemostasis could affect what components of the unstable platelet plug?

Answer 3

Vessel wall - ageing and steroids can damage the endothelium
Von Willebrand factor - vWF disease means that you have no vWF
Platelets - warfarin and other drugs affect platelets. Thrombocytopenia.

Question 4

Describe the pattern of bleeding of a defect in primary haemostasis.

Answer 4

IMMEDIATE - prolonged nose bleeds, easy bruising, menorrhagia, prolonged gum bleeding

Question 5

What is a characteristic feature of thrombocytopenia?

Answer 5

Petechiae

Question 6

What is the main role of secondary haemostasis?

Answer 6

To produce fibrin from fibrinogen and stabilise the platelet plug by forming an insoluble mesh around it.

Question 7

Why is there a lag between the administration of a tissue factor trigger and the thrombin burst?

Answer 7

This is when cofactors and clotting factors are synthesised.

Question 8

State some other causes of problems with secondary haemostasis.

Answer 8

Liver disease (failure to produce clotting factors), drugs, consumption of clotting factors

Question 9

What is DIC?

Answer 9

Disseminated intravascular coagulation - widespread activation of the coagulation cascade
Leads to consumption of the clotting factors - that’s why it’s also called consumptive coagulopathy

Question 10

What is haemophilia defined as?

Answer 10

Failure to generate fibrin to stabilise the platelet plug

Question 11

Describe the pattern of bleeding of defects in secondary haemostasis.

Answer 11

DELAYED - people with defects in secondary haemostasis are generally fine with small cuts. They bleed deeper into joints and muscles. Do NOT tend to bleed excessively from small cuts (because the primary haemostasis is fine)

Question 12

What is the hallmark of haemophilia?

Answer 12

Haemarthrosis - bleeding into joints

Question 13

State some defects of clot stability.

Answer 13

Excess fibrinolytic (tPA)
Deficient antifibrinolytic (antiplasmin)

Question 14

What are the consequences of thromboembolism?

Answer 14

Thrombophlebitic syndrome

Pulmonary hypertension

Question 15

How does risk of thrombosis change with age?

Answer 15

Increases

Question 16

What are the three components of Virchow’s triad?

Answer 16

Hypercoagulability
Vessel wall injury
Stasis

Question 17

Why is pregnancy associated with an increase in the risk of thrombosis?
.

Answer 17

Pregnancy involved reduced mobility and reduced flow and a decrease in protein S meaning that blood becomes procoagulant

Question 18

What is the only circumstance in which thrombolytic therapy is given? Why is it not given more often?

Answer 18

STROKE

Because giving thrombolytic therapy increases the risk of bleeding.

Question 19

What happens in haemophilia?

Answer 19

Deficiency of factor 8 or factor 9. Massively slows down the production of thrombin and so there is no real thrombin burst. Not much fibrin mesh is formed and so the clot is not stabilised.