Bleeding Disorders Quiz (BMS Learning Outcomes)

Haemostasis and Bleeding Disorders

• Haemostasis is the physiological response preventing blood loss after injury. The process involves vasoconstriction, platelet activation, and coagulation cascade activation.

Classifications of Bleeding Disorders

• Disorders of Blood Vessels:

  • Inherited: Connective Tissue Disorders (e.g., Ehlers-Danlos Syndrome), Hereditary haemorrhagic telangiectasia (HHT)
  • Acquired: Severe infections (e.g., meningococcal, typhoid), drugs (e.g., sulphonamides), vitamin C deficiency, senile purpura

• Disorders of Platelets:

  • Thrombocytopenia: Reduced platelet count (<150 x 10⁹/L). Causes include decreased production, destruction, or dysfunction.
    • Idiopathic Thrombocytopenic Purpura (ITP): Autoimmune disorder where immune system attacks platelets. Two forms:
      • Acute: Post-viral (e.g., chickenpox), self-limiting, common in children.
      • Chronic: Any age, symptoms persist from 6 months to lifelong.

• Liver Disease:

  • The liver synthesizes clotting factors (I, II, VII, IX, X, XI).
  • Liver failure impairs vitamin K absorption (needed for clotting factor synthesis).
  • Prolonged Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) occur in chronic liver disease.
  • Post-operative bleeding risks in alcohol-dependent patients are due to decreased clotting factors, bone marrow suppression, malnutrition, and alcohol-enhanced effects of antiplatelet drugs.

• Renal Disease:

  • Chronic renal failure impairs haemostasis due to decreased platelet production/adhesion, reduced platelet factor 3, vasodilation, and heparin use in haemodialysis.

• Disorders of Coagulation:

  • Inherited:

    • Haemophilia A: Most common, X-linked recessive, Factor VIII deficiency. Symptoms: prolonged bleeding (nosebleeds, bleeding gums, easy bruising, joint pain).
    • Haemophilia B (Christmas Disease): Less common, X-linked recessive, Factor IX deficiency; similar symptoms to Haemophilia A
    • Von Willebrand Disease: Common hereditary coagulation abnormality, deficiency/dysfunction of von Willebrand Factor (vWF). vWF carries factor VIII and mediates platelet function. Presentation varies; treated with desmopressin, tranexamic acid, or factor VIII replacement.

  • Acquired: Liver disease, hematological malignancy, anticoagulant drugs (e.g., Warfarin, DOACs).

Medical Conditions and Drug Therapies Affecting Bleeding Risk

• Antiplatelet Drugs: Used to prevent blood clots in conditions like heart disease, stroke, and after stents. Examples include aspirin, clopidogrel, dipyridamole, ticagrelor, prasugrel.

• Anticoagulant Drugs: Used to prevent blood clots in conditions like stroke, deep vein thrombosis, and atrial fibrillation.

  • Warfarin: Vitamin K antagonist, impairs synthesis of factors II, VII, IX, X. Monitored by INR; widely used, but with interactions.
  • Direct Oral Anticoagulants (DOACs): Rivaroxaban, apixaban, edoxaban, dabigatran. Directly inhibit specific clotting factors. Do not require regular INR monitoring (generally safer).
  • Injectable Anticoagulants (e.g., Heparin): Short half-life, used in hospitals, used in patients with deep vein thrombosis, and after surgery.

This quiz covers the essential concepts related to haemostasis and various bleeding disorders. Learn about the physiological mechanisms that prevent blood loss and explore the classifications of bleeding disorders, including inherited and acquired conditions. Test your knowledge on platelet disorders and their implications.