Pulmonary embolism

A pulmonary embolism (thromboembolism) occurs when a blood clot, generally a venous thrombus, becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs. Symptoms may include difficulty breathing, pain during breathing, and more rarely circulatory instability and death. Treatment is with anticoagulant medication, such as warfarin.

Signs, symptoms and risk factors

Clinical presentation

Signs of PE are sudden-onset dyspnea (shortness of breath, 73%), tachypnea (rapid breathing, 70%), chest pain of "pleuritic" nature (worsened by breathing, 66%), cough (37%), hemoptysis (coughing up blood, 13%), and in severe cases, hypotension, shock, loss of consciousness, and death. Although most cases have no clinical evidence of deep venous thrombosis in the legs, findings that indicate this may aid in the diagnosis.

Related Topics:
Dyspnea - Tachypnea - Chest pain - Cough - Hemoptysis - Hypotension - Shock - Loss of consciousness - Deep venous thrombosis

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Electrocardiography (ECG) may occasionally (up to 20%) show right heart strain (the "S1Q3T3 pattern", the McGinn-White pattern).

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Risk factors

The most common sources of embolism are pelvic vein thromboses or proximal leg deep venous thrombosis (DVTs). Any risk factor for DVT also increases the risk that the venous clot will dislodge and migrate to the lung circulation, which happens in up to 15% of all DVTs.

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Risk factors for DVT and PE (together "venous thromboembolism"/VTE) can be divided into genetic, acquired and circumstantial causes. In many occasions, more than one risk factor is present:

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• Genetic ("thrombophilia")
• Factor V, Leiden type (3% of the population are heterozygous for FVL).
• Prothrombin mutation (G20210A).
• Protein C deficiency.
• Protein S deficiency.
• Antithrombin III deficiency.
• High homocysteine levels due to MTHFR mutation.
• Plasminogen and fibrinolysis disorders.
• Acquired
• antiphospholipid antibodies
• anticardiolipin antibodies and/or
• lupus anticoagulants
• Renal disease (renal loss of antithrombin)
• Paroxysmal nocturnal hemoglobinuria
• Use of the oral contraceptive pill
• Circumstantial
• Immobilisation, e.g. after-
• Surgery
• Trauma
• Use of oral contraceptives
• Obesity
• Pregnancy
• Cancer (Trousseau's syndrome)