Pulmonary embolism corresponds to the occlusion of pulmonary arteries by clots (thrombi) originating from different anatomical regions, usually the large veins of the lower limbs or the pelvis. Risk factors for pulmonary embolism are pathologies that impair venous return, those that lead to endothelial damage or dysfunction, and underlying hypercoagulable states. Symptoms of pulmonary embolism are nonspecific and include dyspnoea, pleural pain, and in severe cases faintness, presyncope, syncope, or cardiopulmonary arrest. Signs are also non-specific and may include tachypnea, tachycardia and, in more severe cases, hypotension. Diagnosis of pulmonary embolism is most often made by CT angiography, although a ventilation/perfusion scan is sometimes necessary. Treatment for pulmonary embolism includes blood thinners and sometimes systemic or catheter-directed thrombolysis or catheter ablation or surgery. When anticoagulation is contraindicated, an inferior vena cava filter should be placed. Preventive measures include blood thinners and/or mechanical compression devices applied to the legs of hospitalized patients.
For a given patient, the score allowing the estimation of the clinical probability is obtained by adding the points corresponding to each variable. The clinical probability is low if the score is less than 2. It is intermediate if the score is between 2 and 6 inclusive. It is strong if the score is greater than or equal to 7. An embolism is “improbable” if the score is less than or equal to 4. An embolism is “probable” if the score is greater than or equal to 5.