Bleeding Disorders + Thrombophilia Flashcards
What is the most common cause of primary haemostatic failure?
Thrombocytopenia (usually acquired)
What are the two main mechanisms of thrombocytopenia?
Reduced production –> marrow problem
Increased destruction –> DIC, ITP, hypersplenism
What might cause function defects in platelets?
Drugs e.g. aspirin, NSAIDs
Renal failure
How is vWF deficiency inherited?
Autosomal dominant
Which conditions may cause a multiple factor deficiency?
Liver failure
Vitamin K deficiency / warfarin therapy
DIC
How would PT and APTT be affected by a multiple factor deficiency?
Both would be prolonged
Where are coagulation factors synthesised?
Hepatocytes (reduced in liver failure)
Which factors are carboxylated by vitamin K?
2, 7, 9, 10
What are the causes of vitamin K deficiency?
Poor dietary intake Malabsorption Obstructive jaundice (bile required for absorption) Warfarin (vitamin K antagonist) Haemorrhagic disease of newborn
What is DIC?
Excessive + inappropriate activation of the haemostatic system –> primary, secondary + fibrinolysis
What are the features of DIC?
Microvascular thrombus formation –> end organ failure
Clotting factor consumption –> bruising, purpura + generalised bleeding
What are some causes of DIC?
Sepsis
Obstetric emergencies
Malignancies
Hypovolaemic shock
How is DIC managed?
Treat underlying cause
Platelet + plasma transfusions
Fibrinogen replacement
What is the pattern of inheritance of haemophilia?
X-linked
Which type of haemophilia is most common?
Haemophilia A
What causes the bleeding in haemophilia A?
Factor 8 deficiency
What causes the bleeding in haemophilia B?
Factor 9 deficiency
What are the features of haemophilia?
Haemarthrosis
Haematoma in muscles
Intracranial haemorrhage
Prolonged bleeding after procedure/dental work
Which blood result would be suggestive of haemophilia?
Isolated prolonged APTT
PT not affected
How is haemophilia A managed?
Avoid contact sport IV factor 8 concentrate - weekly for prophylaxis or until bleeding stops if acute Desmopressin - for acute bleeds in mild haemophilia
What is INR?
Standardised norm for PT
How do the clots differ between arterial and venous thrombosis?
Arterial:
- high pressure, atherosclerosis
- platelet rich thrombus
Venous:
- low pressure so platelets not activated
- coagulation cascade –> fibrin rich clot
Which drugs are used to treat arterial thrombosis?
Aspirin + other anti-platelets
Which drugs are used to treat venous thrombosis?
Heparin, warfarin + DOACs
What is thrombophilia?
Disorder (inherited or acquired) which predisposes to thrombosis
Give some examples of hereditary thrombophilias
Factor 5/Leiden Prothrombin 20210 mutation Antithrombin deficiency Protein C deficiency Protein S deficiency
When should you consider screening for inherited thrombophilias?
Venous thrombosis < 45 years old
Recurrent venous thrombosis
Usual venous thrombosis
FHx of venous thrombosis/thrombophilia
Give an example of an acquired thrombophilia?
Antiphospholipid antibody syndrome
What are the features of antiphospholipid antibody syndrome?
Recurrent arterial and venous thrombosis
Recurrent foetal loss
Mild thrombocytopenia
Which drugs are used to manage antiphospholipid antibody syndrome?
Aspirin + warfarin
–> as activation of both primary + secondary haemostasis
