Flashcards in Clinical Haemostasis and Thrombosis Deck (19)
What clinical feature is common to all bleeding disorders?
What constitutes the unstable platelet plug?
Exposed collagen - von Willebrand factor - platelets
A disease of primary haemostasis could affect what components of the unstable platelet plug?
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.
Describe the pattern of bleeding of a defect in primary haemostasis.
IMMEDIATE - prolonged nose bleeds, easy bruising, menorrhagia, prolonged gum bleeding
What is a characteristic feature of thrombocytopenia?
What is the main role of secondary haemostasis?
To produce fibrin from fibrinogen and stabilise the platelet plug by forming an insoluble mesh around it.
Why is there a lag between the administration of a tissue factor trigger and the thrombin burst?
This is when cofactors and clotting factors are synthesised.
State some other causes of problems with secondary haemostasis.
Liver disease (failure to produce clotting factors), drugs, consumption of clotting factors
What is DIC?
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
What is haemophilia defined as?
Failure to generate fibrin to stabilise the platelet plug
Describe the pattern of bleeding of defects in secondary haemostasis.
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)
What is the hallmark of haemophilia?
Haemarthrosis - bleeding into joints
State some defects of clot stability.
Excess fibrinolytic (tPA)
Deficient antifibrinolytic (antiplasmin)
What are the consequences of thromboembolism?
How does risk of thrombosis change with age?
What are the three components of Virchow's triad?
Vessel wall injury
Why is pregnancy associated with an increase in the risk of thrombosis?
Pregnancy involved reduced mobility and reduced flow and a decrease in protein S meaning that blood becomes procoagulant
What is the only circumstance in which thrombolytic therapy is given? Why is it not given more often?
Because giving thrombolytic therapy increases the risk of bleeding.