Bleeding disorders: overview
- Topic
Bleeding comes from weak vessels, too few or faulty platelets, or missing clotting factors. Where and how a patient bleeds shows which.
What it is
Haemostasis depends on the vessel wall, platelets and the coagulation cascade, and a hemorrhagic diathesis can arise from a defect in any of them. Vessel and platelet defects cause mucocutaneous bleeding: petechiae, purpura, nosebleeds, gum bleeding and heavy menses. Clotting factor deficiencies cause deep bleeding into joints and muscles and delayed oozing after surgery or dental extraction. A short set of tests (platelet count, PT, PTT, fibrinogen, D-dimer, platelet function tests) usually sorts the problem.
Step by step
- Vessel injury exposes collagen and von Willebrand factor; reflex vasoconstriction slows flow.
- Platelets adhere through GPIb–vWF, activate, release ADP and thromboxane and aggregate through GPIIb/IIIa–fibrinogen.
- Tissue factor triggers the cascade; thrombin makes fibrin that stabilizes the platelet plug.
- A defect in the wall or platelets fails the first, immediate plug: mucosal and skin bleeding.
- A factor defect lets a plug form but not hold: delayed and deep bleeding.
Sorting bleeding disorders with basic tests
| Defect | Bleeding pattern | Platelet count | PT | PTT |
|---|---|---|---|---|
| Vessel wall (scurvy, vasculitis, HHT) | Petechiae, purpura, mucosal | Normal | Normal | Normal |
| Thrombocytopenia (ITP, marrow failure) | Petechiae, mucosal, intracranial risk | Low | Normal | Normal |
| Platelet function (Glanzmann, Bernard–Soulier, aspirin, uraemia) | Mucocutaneous | Normal (low and large in Bernard–Soulier) | Normal | Normal |
| von Willebrand disease | Mucosal, heavy menses | Normal | Normal | Normal or long |
| Haemophilia A or B | Joints, muscles, delayed | Normal | Normal | Long |
| DIC, liver disease, vitamin K deficiency | Mixed, oozing from sites | Low in DIC, normal otherwise | Long | Long or normal |
Clinical notes
- A personal and family history (surgery, tooth extraction, menses, childbirth) is the best screening tool.
- Mixing studies tell factor deficiency (corrects) from an inhibitor (does not).
Test yourself
Think of the answer, then tap the question to see it.
What bleeding pattern suggests a clotting factor deficiency?
Deep bleeding into joints and muscles and delayed bleeding after trauma or surgery, without petechiae.
Which basic tests are normal in vessel-wall bleeding disorders?
Platelet count, PT and PTT are all normal.
What is the lab pattern of DIC?
Low platelets, prolonged PT and PTT, low fibrinogen and high D-dimer.
Elsewhere in DurgiPedia
- Coagulation tests: PT/INR, aPTT and platelets
- Primary hemostasis and platelets
- The coagulation cascade
- Bleeding syndromes: platelet vs coagulation pattern
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Bleeding Disorders | MedlinePlus (MedlinePlus, US National Library of Medicine, 2026); Platelet Disorders | MedlinePlus (MedlinePlus, US National Library of Medicine, 2026).
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Representative model, for educational purposes only.