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