Pulmonary embolism

Complete occlusion of a peripheral pulmonary artery usually results in a pulmonary infarction with pleuritic chest pain and haemoptysis. When the blood clot is lodged in more proximal pulmonary arteries and is not occlusive, pulmonary infarction does not occur and pulmonary embolism might present as isolated dyspnoea. Massive pulmonary embolism is caused by large bilateral proximal clots resulting in haemodynamic collapse.1 #### Case scenario A non-smoking, previously well woman in her 70s complained of recent onset of dyspnoea. She had no cardiovascular or thromboembolic risk factors and clinical examination was normal apart from a heart rate of 96 beats per minute. With no clear explanation for the symptoms, her general practitioner applied a decision rule (table⇓) to evaluate the clinical probability of pulmonary embolism. The result was intermediate, prompting him to request a D-dimer level, which was raised. He referred the patient to hospital, where pulmonary embolism was confirmed on computed tomography. View this table: #### How common is it?