Bleeding Disorders Flashcards
What are vascular abnormalities that can affect bleeding?
Hereditary
Acquired - vasculitis (Henoch Schonlein purpura)
What are acquired causes of thrombocytopenia?
Reduced production (marrow problem)
Increased destruction
What are causes of peripheral platelet destruction?
Coagulopathy - disseminated intravascular coagulation (DIC)
Autoimmune - immune thrombocytopenic purpura (ITP)
Hypersplenism
What are acquired platelet functional defects?
Drugs (e.g. aspirin, NSAIDs)
Renal failure
Von willebrand factor deficiency is acquired how?
Autosomal dominant
Common
Variable severity -. usually mild
What is the commonest cause of primary haemostatic failure?
Thrombocytopenia
Usually acquired
Causes: marrow failure, peripheral destruction
What are causes of multiple factor deficiencies which then causes failure of fibrin clot formation?
Liver failure
Vitamin K deficiency / warfarin therapy
Complex coagulopathy (DIC)
Prolonged APTT + PT
All coagulation factors are synthesised where?
In hepatocytes, so these are reduced in liver failure
What clotting factors are carboxylated by vitamin K, which is essential for function?
1972
(factors II, VII, IX, X)
What are sources of vitamin K?
Diet
Intestinal synthesis (by bacteria)
How do we absorb vitamin K?
Absorbed upper intestine
Requires bile salts for absorption
What are causes of vitamin K deficiency?
Poor diet intake
Malabsorption
Obstructive jaundice
Vitamin K antagonists (warfarin)
Haemorrhagic disease of the newborn
What is disseminated intravascular coagulation?
Excessive and inappropriate activation of haemostatic system (primary, secondary, fibrinolysis)
Microvascular thrombus formation (end organ failure)
Clotting factor consumption (bruising, purpura, generalised bleeding)
What are causes of DIC?
Sepsis
Obstructive emergencies
Malignancy
Hypovolaemic shock
How do we treat DIC?
Treat underlying cause
Replacement therapy - platelet transfusions, plasma transfusions, fibrinogen replacement
What is haemophilia?
X-linked hereditary disorder in which abnormally prolonged bleeding recurs episodically at one or few sites on each occassion
What are the main types of haemophilia?
Haemophilia A (factor VIII deficiency) -5x more common
Haemophilia B (Factor IX deficiency)
What is the pathophysiology of haemophilia?
No abnormality of primary haemostasis
Bleeding from medium to large blood vessels
Mild, moderate and severely affected families on factor VIII/IX level
What are clinical features of severe haemophilia?
Recurrent haemarthroses
Recurrent soft tissue bleeds (bruising in toddlers)
Prolonged bleeding after dental extractions, surgery and invasive procedures
Haemophilia A and B have what prolonged test?
Isolated prolonged APTT
