Venous thromboembolism

Venous thromboembolism (VTE) refers to a thrombus which originates in a vein. The most important types are deep vein thrombosis and pulmonary embolism.

VTE is a major source of mortality and morbidity, and its incidence is increasing. In the US alone it causes > 200 000 deaths annually, more than HIV, motor vehicle accidents, and breast cancer combined. VTE is preventable, and a major cause of preventable death. Many patients with VTE develop recurrent VTE later.

Etiology

VTE occurs due to Virchow’s triad, three categories of factors which contribute to thrombosis:

• Stasis (alteration in normal blood flow)
• Hypercoagulability (alteration in the constitution of blood predisposing to thrombosis)
• Endothelial injury

There are many risk factors for VTE, which we can categorise according to Virchow’s triad:

• Stasis
  • Old age
  • Recent immobility (especially after surgery or trauma)
  • Heart failure
  • Paralysis
  • Obesity
  • Varicose veins
• Hypercoagulability
  • Cancer
  • Smoking
  • High oestrogen state
  • Pregnancy
  • Thrombophilia
  • Sepsis
• Endothelial damage
  • Surgery
  • Previous VTE
  • Trauma

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