Virchow's triad

• Venous stasis:

  • Prolonged immobilisation = bed rest > 5 days, major surgery within the last 2 months, recent trauma or fracture, paralysis of the lower limb, long-hall flights
  • Venous insufficiency of the lower limb
• Hypercoagulable state:

  • Active malignancy
  • Pregnancy and postnatal period
  • Thrombophilia - antiphospholipid syndrome, factor V Leiden mutation
  • Oestrogen - COCP/HRT
• Endothelial injury:

  • Trauma
  • Surgery
  • Venous harvest (CABG)
  • Cigarette smoking
  • Obesity