A pulmonary embolism (also called a PE) is a blockage of either the pulmonary artery (the main blood vessel carrying blood from the heart to the lungs) or one its branches. A PE usually occurs when a venous thrombus (a blood clot from a vein) becomes dislodged and travels through the blood to one of the lungs.

Symptoms usually come on suddenly and may include difficulty breathing, pain in the chest during breathing, cough, and even coughing up blood.

The most common sources of pulmonary embolus are DVTs. This means that the risk factors for PEs are the same as those for DVTs. These include any long period of immobilisation (such as hospitalisation or air travel), obesity, some forms of hormone based contraception, and smoking.

Anticoagulants, such as warfarin, are the main treatment for PE. Usually, you will be started on a heparin while warfarin starts working, and will then stay on warfarin for 3 to 6 months. If you have had a DVT or PE in the past you may need to stay on warfarin for longer than this.