Venous thromboembolism: diagnosis and management of pulmonary embolism
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Pulmonary embolism (PE) affects 0.5-1 per 1000 people in the general population each year, and is one of the most common preventable causes of death among hospitalised patients. The clinical diagnosis of PE is unreliable and must be confirmed objectively with ventilation perfusion scanning or computed tomography pulmonary angiography. The diagnosis of PE can be reliably excluded, without the need for diagnostic imaging, if the clinical pretest probability for PE is low and the D-dimer assay result is negative. The initial treatment of PE is low-molecular-weight heparin or unfractionated heparin for at least 5 days, followed by warfarin (target international normalised ratio [INR], 2.0-3.0) for at least 3-6 months. Patients with a high clinical pretest probability of PE should commence treatment immediately while awaiting the results of the diagnostic work-up. Thrombolysis is indicated for patients with objectively confirmed PE who are haemodynamically unstable. Percutaneous transcatheter or surgical embolectomy may be life-saving in patients ineligible for, or unresponsive to, thrombolytic therapy. Unresolved issues in the management of venous thromboembolism include the roles of thrombophilia testing, thrombolysis for the treatment of stable PE patients who present with right ventricular dysfunction, and new anticoagulants; and the duration of anticoagulation for first unprovoked venous thromboembolism.