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PA20.1-2 | Welcome to Coagulation Factor Disorders — Haemophilia & vWD
Learning Objectives
- Distinguish the clinical bleeding pattern of secondary haemostasis failure (deep-tissue bleeding) from primary haemostasis failure (mucocutaneous bleeding).
- Describe the aetiology, pathogenesis, and laboratory features of Haemophilia A and Haemophilia B.
- Explain the pathophysiology of von Willebrand disease and its unique dual role in platelet adhesion and factor VIII stabilisation.
- Interpret PT and aPTT patterns to localise defects in the intrinsic, extrinsic, and common pathways.
- Describe acquired coagulation factor deficiencies due to liver disease and vitamin K deficiency.
- Apply mixing study logic to distinguish factor deficiency from inhibitor.
INSTRUCTIONS
Secondary haemostasis — the coagulation cascade — converts a fragile platelet plug into a stable fibrin clot. When this step fails, bleeding is deep, delayed, and recurrent. This module builds on the coagulation cascade covered in SDL1 to explain why haemophilias cause haemarthroses, why von Willebrand disease straddles both primary and secondary haemostasis, and how a two-tube mixing study can distinguish whether a patient is missing a factor or has made an antibody against one.
References
- Robbins & Kumar Basic Pathology, 11th ed., Ch 13 — Red Cell and Bleeding Disorders (textbook)
- Harsh Mohan Textbook of Pathology, 8th ed., Ch 12 — Disorders of Bleeding and Coagulation (textbook)
Version 2.0 | NMC CBUC 2024