Flashcards in Bleeding and coagulation Deck (54)
What is haemostasis?
The arrest of bleeding and maintenance of vascular patency
What is primary and secondary haemostasis?
Primary haemostasis is the formation of a platelet plug
Secondary haemostasis is the formation of a fibrin clot
Where are platelets formed?
Platelets are formed in the bone marrow by budding from megarokaryocytes
What is the life span of a platelet?
What are some of the possible causes of failure of platelet plug formation?
E.g reduced collagen in blood vessels in elderly patients and inherited causes such as marfan's
Thrombocytopenia due to anti-platelet medications and NSAIDs
Von Willebrand disease
Lack of vitamin C e.g scurvy
Which is generally more severe, failure of primary haemostasis or failure of secondary haemostasis?
Failure of secondary haemostasis
How does failure of platelet plug formation present?
Spontaneous bruising and purpura (usually in the lower limbs due to gravity)
Mucosal bleeding (epistaxis, GI, conjunctival and menorrhagia)
Intracerebral bleeds in severe cases
What is the screening test for primary haemostasis?
What are the screening tests for secondary haemostasis?
Activated partial thromboplastin time
What are some of the naturally occurring anticoagulants?
Protein C and S
Does prothrombin time test the extrinsic or the intrinsic pathway?
It measures the propagation side of fibrin clot formation
What is the normal range for prothrombin time?
What are some of the causes of a prolonged PT?
Vitamin K deficiency (premature babies and ITU patients)
Does the APTT test the extrinsic or the intrinsic pathway?
Measure the amplification side of fibrin clot formation
What is the normal range for APTT?
What are some of the possible causes of prolonged APTT?
Thrombocytopenia is the most common cause of primary haemostatic failure. What are some of the possible cause of thrombocytopenia?
Immune thrombocytopenic purpura
What is immune thrombocytopenic purpura?
An autoimmune cause of thrombocytopenia which involves antibodies against platelets
how is immune thrombocytopenic purpura managed?
VWF deficiency can be acquired or hereditary. Which is more common?
What mode of inheritance does VWF disease involve?
VWF affects men and women equally, so why are men less likely to be diagnosed?
Women are more likely to present as they may have the symptom of menorrhagia
The condition may not become apparent in men until they have an accident or operation and notice abnormal bleeding
Is haemophilia due to a single or multiple clotting factor deficiencies?
Single clotting factor deficiency
Where are coagulation factors synthesised?
In hepatocytes in the liver
What happens to coagulation factors in liver failure?
Coagulation factors are reduced
What are the four clotting factors?
II, VII, IX and X
(2,7,9 and 10)
Where is vitamin K absorbed?
What does it require for absorption?
Vitamin K is absorbed in the upper intestine
Requires bile salts for absorption
What are some of the possible causes of vitamin K deficiency?
(e.g pancreatic cancer)
Haemorrhagic disease of the newborn
Why does DIC occur?
All the clotting factors are used up in thrombus formation