The clot can then dislodge from where it originates and travel in the blood stream to lodge in one of the pulmonary arteries, the arteries that send blood to the lungs.

A major pulmonary embolism can be fatal. If you think you may have a pulmonary embolism, go to the nearest emergency department or dial triple zero (000) to call an ambulance.

Pulmonary embolism symptoms

Most people with pulmonary embolism have some symptoms, but they can be mild.

Symptoms can include:

• breathlessness, particularly if new or sudden
• rapid breathing
• chest pain
• cough
• fainting
• low blood pressure
• fast heart rate.

Other symptoms include:

• swelling of one or both legs, usually in the calf
• clammy skin
• fever and sweating
• feeling lightheaded or dizzy.

Pulmonary embolism risk factors

You are also at higher than usual risk of a pulmonary embolism if you have been immobile for long periods such as extended travel or hospitalisation.

You are at a higher than usual risk of having a pulmonary embolism if you smoke, or use the oral contraceptive pill or hormone replacement therapy, or smoke and take either of those medications.

You are at a higher than usual risk of having a pulmonary embolism if you are or have recently been pregnant or overweight.

You are at a higher than usual risk of having a pulmonary embolism if you have or have had:

• major surgery
• major trauma
• chemotherapy
• a severe illnesses such as heart disease, cancer or respiratory failure
• thrombophilia, a condition in which the blood clots easily
• varicose veins.

Pulmonary embolism diagnosis

If your doctor thinks you may have a pulmonary embolism, they will talk to you and examine you.

You will be asked to have some tests, such as:

• blood tests
• electrocardiogram (ECG)
• imaging such as a chest X-ray, CT scan, ultrasound or one known as a ventilation-perfusion scan, which measures both air flow and blood flow in your lungs.

The Royal Australian and New Zealand College of Radiologists recommend that if your doctor suspects you have a pulmonary embolism, you should ask about the most appropriate test for diagnosis. For further information, visit the Choosing Wisely Australia website.

Complications of pulmonary embolism

A small pulmonary embolism might cause few problems. But a large pulmonary embolism is serious, and can cause heart problems, lung problems or even sudden death.

About a third of people who have a pulmonary embolism have another one later.

Pulmonary embolism treatments

Emergency treatment of pulmonary embolism involves:

• oxygen through a mask
• anticoagulant medication to dissolve blood clots
• surgery to remove a clot (in very serious cases).

Pulmonary embolism prevention

If you are at risk of having a pulmonary embolism, you should not smoke. You will learn what medications to avoid, and you may need medication to thin the blood. A few people are advised to have surgery to put a small filter in the main vein in the abdomen, in an effort to catch clots before they reach the lungs.

If you are having surgery, your doctors and nurses will reduce your risk of having a pulmonary embolism by:

• keeping you in hospital for as short a time as possible
• offering medication, compression stockings and perhaps a machine that pumps the leg muscles while a person is unable to walk, to prevent blood clots forming in the legs of patients following surgery.