General pathology · Hemodynamic disorders
Thrombosis and Virchow's triad !
- Mechanism
A thrombus is a clot that forms inside a living vessel. It comes from endothelial damage, abnormal flow or blood that clots too easily.
Updated 2026-11-01
What it is
Thrombosis is hemostasis switched on in the wrong place at the wrong time: inside an intact vessel, or in response to a small injury. Virchow described the three factors that favour it: endothelial injury, abnormal flow (stasis or turbulence) and hypercoagulability. In arteries and the heart endothelial injury dominates; in veins, stasis. Thrombi cause infarcts and emboli, the leading causes of death worldwide.
Step by step
- The endothelium is injured or activated (cytokines, turbulent flow, tobacco toxins).
- Platelets stick to exposed collagen through von Willebrand factor.
- They activate, release ADP and thromboxane A2 and recruit more platelets.
- Tissue factor starts the cascade; thrombin turns fibrinogen into fibrin.
- Stasis keeps activated factors from being washed away and inhibitors from arriving.
- The thrombus grows if formation outpaces fibrinolysis; it may occlude or break off.
Virchow’s triad in practice
| Factor | What happens | Examples |
|---|---|---|
| Endothelial injury | Collagen and tissue factor are exposed; antithrombotic protection is lost | Ruptured atheromatous plaque, myocardial infarction, vasculitis, catheters, smoking |
| Stasis | Platelets touch the wall; activated factors are not diluted | Immobility, varicose veins, atrial fibrillation, aneurysms, dilated ventricle |
| Turbulence | Damages the endothelium and creates pockets of stasis | Arterial branch points, diseased valves |
| Hypercoagulability | More clotting factors or fewer natural anticoagulants | Factor V Leiden, cancer, pregnancy, estrogens, antiphospholipid syndrome |
Clinical notes
- Deep vein thrombosis after orthopaedic surgery, childbirth or immobilisation: stasis is the main factor.
- Myocardial infarction: thrombosis on a ruptured atheromatous plaque in a coronary artery.
- Polycythemia vera: thick blood (hyperviscosity) causes stasis in small vessels.
Test yourself
Think of the answer, then tap the question to see it.
What are the three parts of Virchow’s triad?
Endothelial injury, abnormal blood flow (stasis or turbulence) and hypercoagulability.
Which part of the triad dominates in deep vein thrombosis?
Venous stasis, for example from immobility or surgery.
Which molecule ties platelets to subendothelial collagen?
Von Willebrand factor, which binds platelet glycoprotein Ib.
Why does atrial fibrillation predispose to thrombosis?
Because the atrium does not contract well and blood stagnates, above all in the left atrial appendage.
Related
- Hypercoagulable states: inherited and acquired
- Arterial vs venous thrombi; mural thrombi and lines of Zahn
- What happens to a thrombus: propagation, embolism, dissolution, organization
- Pulmonary thromboembolism: where it comes from and what it does
- Systemic (arterial) thromboembolism
Related conditions
- Deep vein thrombosis
- Myocardial Infarction (Heart Attack)
- Cerebral venous sinus thrombosis
- Pulmonary embolism
- Atrial fibrillation
- Ischaemic stroke
- Portal vein thrombosis
- Renal vein thrombosis
- Budd-Chiari syndrome
- Abdominal aortic aneurysm
- Polycythaemia vera
- Superficial thrombophlebitis (superficial vein thrombosis)
Elsewhere in DurgiPedia
- Thrombosis and bleeding: Virchow's triad and hemostatic defects
- The coagulation cascade
- Primary hemostasis and platelets
- Fibrinolysis and natural anticoagulants
- Nitric oxide (NO)
- Thromboxane A₂ (TXA₂)
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: About Venous Thromboembolism (Blood Clots) (Centers for Disease Control and Prevention (CDC), 2025); Venous Thromboembolism - What Is Venous Thromboembolism? | NHLBI, NIH (National Heart, Lung, and Blood Institute (NHLBI), 2022); Blood Clots | Hypercoagulability | MedlinePlus (MedlinePlus, US National Library of Medicine, 2023).
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Representative model, for educational purposes only.