Venous thromboembolism - NYSORA

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Venous thromboembolism

Learning objectives

  • Describe the mechanisms and risk factors for venous thromboembolism
  • Prevent perioperative venous thromboembolism
  • Diagnose and manage venous thromboembolism


  • Venous thromboembolism (VTE) is a major cause of morbidity and mortality in both hospital and community settings 
  • Most preventable cause of mortality in hospitalized patients
  • Encompasses deep vein thrombosis (DVT) and pulmonary embolism (PE)
  • DVT occurs when red blood cells, fibrin, platelets, and leucocytes form a mass within an intact deep vein
  • Signs & symptoms are nonspecific and only occur in up to 50% of patients
  • PE occurs in about a third of patients with a DVT
  • Adequate perioperative thromboprophylaxis is essential to prevent perioperative VTE

Risk factors

  • Three main factors that cause thrombosis:
    • Alterations in blood flow (stasis and turbulence)
    • Vascular endothelial injury
    • Alterations in the blood coagulability
  • Risk factors:
Stasis–endothelial injuryThrombophiliasMedical conditionsMedications Other
Indwelling venous deviceActivated protein C resistanceMalignancy (solid tumour and myeloproliferative disorders)Oral contraceptive use (combined only)Increasing age
Surgery (abdominal, pelvic, orthopedic most commonly)Factor V LeidenPregnancy, postpartumHormone replacement therapySmoking
Major trauma, burnsProthrombin gene mutation G20210AMyocardial infarctionChemotherapy (including tamoxifen)
Prolonged travelHyperhomocysteinemiaCongestive heart failure
Paralysis (including anesthesia for >30 min)Anticardiolipin antibodiesObesity
Varicose veinsLupus anticoagulantInflammatory bowel disease
Elevated factor VIII levelNephrotic syndrome
Protein C deficiencyHistory of VTE
Protein S deficiencyHeparin-induced thrombocytopenia
DysfibrinogenemiaParoxysmal nocturnal hemoglobinuria
Antithrombin deficiency


  • Venous thrombi typically develop at a site of vascular trauma, around intravascular catheters, or in areas of reduced blood flow (e.g., venous valves)
  • Accumulation of fibrin and platelets causes rapid growth in the direction of blood flow
  • Endogenous fibrinolysis results in partial or complete resolution of the thrombus
  • Any residual thrombus may result in incomplete recanalization of the vein, potentially narrowing the lumen and causing valve incompetence
  • Extensive collateral network may develop


venout thromboembolism, vte, mobility, bleeding, prophylaxis, anti-embolism stockings, vascular disease, arteriosclerosis, neuropathy, edema, heat failrue, stroke, pneumatic compression, foot impulse, neuraxial block, unfractionated heparin, low molecular weight heparin, LMWH, warfarin, factor xa, aspirin, danaparoid, fandaparinux, Lepirudin, thrombocytopenia, dextran, physiotherapy


  • DVT
    • Duplex ultrasonography
    • D-dimer blood test
    • Contrast venography
    • MRI
  • PE
    • Computed tomographic pulmonary angiography
    • Ventilation-perfusion scan
    • Pulmonary angiography
    • MRI


  • Preferred DVT treatment: Low molecular weight heparins
  • Maintain anticoagulation for 3-6 months for VTE secondary to transient risk factors and >12 months for recurrent VTE
  • Thrombolytics in severe cases
  • When anticoagulation fails: Inferior vena cava filter
  • Thrombectomy/embolectomy (rarely required)

Suggested reading

  • Gordon RJ, Lombard FW. Perioperative Venous Thromboembolism: A Review. Anesthesia & Analgesia. 2017;125(2).
  • Barker RC, Marval P. Venous thromboembolism: risks and prevention. Continuing Education in Anaesthesia Critical Care & Pain. 2011;11(1):18-23.
  • National Clinical Guideline Centre – Acute and Chronic Conditions (UK). Venous Thromboembolism: Reducing the Risk of Venous Thromboembolism (Deep Vein Thrombosis and Pulmonary Embolism) in Patients Admitted to Hospital. London: Royal College of Physicians (UK); 2010. (NICE Clinical Guidelines, No. 92.) 2, Summary of recommendations. Available from:

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