In this article we will describe 10 key facts and figures about pulmonary embolism: focusing on its symptoms, causes and treatment.
A pulmonary embolism is when a blood clot blocks a blood vessel in your lungs. It can be life-threatening in some people, if not treated quickly.
Pulmonary embolism (PE) is the luminal obstruction of one or more pulmonary arteries; usually by an embolised venous thrombus, but can also be due to an embolised solid, liquid, or gas.
Most PEs originate as thrombi due to deep vein thrombosis (DVT), most frequently in the calf veins.
Other causes include:
Venous thromboembolism (VTE) is an umbrella term encompassing both pulmonary embolism (PE) and deep vein thrombosis (DVT).
Common symptoms of PE include: a sudden (or gradual) onset of shortness of breath, pleuritic chest pain (that is worse when breathing in, moving and coughing; 40%), a tachycardia (rapid heart rate), lightheadedness, and sometimes haemoptysis (coughing up blood).
Pain, redness, and swelling in one leg (usually the calf) may also indicate a blood clot (deep vein thrombosis) that has led to a pulmonary embolism.
Massive pulmonary embolism. Clinical features of a massive PE include:
Note. Any patient with unexplained SOB and a normal chest x-ray should be considered (and treated) as having a PE until otherwise proven.
PEs can be caused by clotting disorders, injury to a vein, surgery, certain medications, and prolonged periods of immobility (e.g. long flights or bed rest).
Note. COVID-19. People who have severe symptoms of COVID-19 have an increased risk of DVT and PE.
Risk factors for DVT include age (especially over 60 years), obesity, smoking, cancer, heart failure, varicose veins, genetic predisposition, pregnancy/oral contraceptive (OC) or hormone replacement therapy (HRT), and a history (or family history) of DVT or PE.
PE is diagnosed through various imaging tests, such as a CT pulmonary angiography (CTPA), a V/Q (ventilation-perfusion) scan, or a Doppler ultrasound of the legs to detect DVT.
These include ECG, chest x-ray and arterial blood gases (ABGs). Although there are typical abnormalities in all three, all three can be normal.
Possible ECG findings include:
Chest x-ray is used to exclude other possible differential diagnoses (e.g. pneumothorax and pneumonia), not to make the diagnosis of PE. Possible chest x-ray findings in PE include:
Unusual signs on chest x-ray. Focal oligaemia, or the Westermark sign, is an area of increased lung transparency distal to an occluded vessel; pulmonary infarction appears on CXR as a pleural-based wedge shaped consolidation, or Hampton’s hump.
Two other signs reflecting vascular patterns may be observed: Fleischner’s sign, related to pulmonary artery enlargement; and Palla’s sign, indicating vascular prominence before an arterial occlusion.
Chest x-ray showing a pleural-based wedge-shaped consolidation in the right lower lobe (Hamptons’ hump; arrow), which was confirmed by CTPA to be a pulmonary infarction, in a patient with acute pulmonary embolism.
Chest x-ray showing enlargement of the main pulmonary artery (Fleischner’s sign; white arrow) and prominence of the right descending pulmonary artery (Palla’s sign; black arrows) in a patient with chronic pulmonary embolism.
Note. Most patients with PE have a normal chest x-ray.
The D-dimer test has a high sensitivity but low specificity for VTE (PE and DVT). Many conditions can result in an elevated D-dimer in the absence of VTE:
Note 1. In these patients, D-dimer testing has no value in diagnosing VTE
Note 2. D-dimer has a good negative predictive value. A negative D-dimer almost certainly excludes PE (and DVT).
If untreated, PE can cause severe complications, including pulmonary hypertension, chronic thromboembolic pulmonary hypertension (CTEPH), heart failure, and death.
Treatment typically involves anticoagulant medications like heparin, warfarin, or newer oral anticoagulants (NOACs) to prevent further clotting. In severe cases, thrombolytic therapy or surgical interventions like embolectomy may be necessary.
Preventive measures include staying active, exercising regularly, maintaining a healthy weight, avoiding prolonged periods of immobility, wearing compression stockings; and, for high-risk individuals (or people who have had 2 or more DVT/PEs), taking blood thinners (warfarin, heparin, direct-acting oral anticoagulant (DOAC)).
Occasionally an inferior vena cava (IVC) filter – inserted by an interventional radiologist – is necessary to prevent further PEs from further DVTs.
The risk of blood clots developing while traveling is low but increases as long-haul travel increases. The following to help prevent blood clots during travel:
The prognosis for PE is very variable. With prompt treatment, the outlook is generally good, but untreated PE can be fatal. Approximately one-third of untreated PE cases are fatal.
In England, 25,000 deaths per year are due to blood clots (PEs that developed after a DVT) that occurred whilst the person was in hospital.
We have described 10 PE (pulmonary embolism) facts and figures, focusing on its symptoms, causes and treatment. We hope it has been helpful.
10 DVT facts
Pulmonary embolism (NHS England)