Pulmonary Embolism (DVT/PE)

Clot formation within the deep venous system, usually of the calf, thigh, or pelvic veins. The clot can cause a local problem at site of formation or dislodge, leading to thromboembolism in various parts of the body, particularly the lungs
(pulmonary embolism).


  • Venous stasis (slowing of blood flow)
  • Increased coagulability states
  • Endothelial injury

Risk factors

  • Immobilisation, prolonged bed rest, surgery, limb paralysis
  • Heart failure, myocardial infarction
  • Blunt trauma, venous injury including cannulation
  • Oral contraceptive pills, pregnancy and postpartum
  • Malignancies and chemotherapy
  • Long distance air travel

Clinical features

  • 50% of cases may be clinically silent
  • Pain, swelling and warmth of the calf, thigh, and groin
  • Dislodgement of the thrombus may lead to pulmonary embolism characterised by dyspnoea, tachycardia, chest pain, hypotension
  • Half of the cases of PE are associated with silent DVT

Differential diagnosis

  • Cellulitis, myositis, phlebitis, contusion
  • For PE: any other cause of dyspnoea and chest pain


  • Compression ultrasound +/- doppler
  • In case of pulmonary embolism: chest CT angiogram
  • Other useful tests (not specific): blood D-dimer, ECG, Chest X ray, echo cardiogram


  • Enoxaparin (Low molecular weight heparin-
    LMWH) 1 mg/kg every 12 hours for at least 5 days

    • No monitoring is required
  • Plus warfarin 5 mg single dose given in the evening, commencing on the same day as the heparin
    • Maintenance dose: 2.5-7.5 mg single dose daily, adjusted according to the INR 2 -3

If enoxaparin not available

  • Unfractionated heparin given as: 5000 units IV bolus and then 1000 units hourly or 17500 units subcutaneuosly 12 hourly for 5 days. Adjust dose
    according to activated partial thromboplastin time (APTT)
  • Or 333 units/kg SC as an initial dose followed by 250 units/kg SC every 12 hours
  • Plus warfarin as above


  • Monitor for bleeding complications
  • See section for treatment of warfarin overdose and PGD 2015 monograph on protamine for excessive heparin dose
  • Do not start therapy with warfarin alone because it initially increases risk of thrombus progression


  • Early mobilisation
  • Prophylaxis with enoxaparin 40 mg SC daily in any acutely ill medical patient and in prolonged admission