Pulmonary Embolism (PE)
A blood clot blocking a pulmonary artery — a medical emergency with variable presentation.
Overview
Pulmonary embolism occurs when a thrombus, usually from a deep leg vein, lodges in the pulmonary arterial circulation. Presentation ranges from mild breathlessness to cardiovascular collapse. Early recognition and anticoagulation save lives.
Symptoms
- • Sudden breathlessness
- • Pleuritic (sharp) chest pain
- • Cough, sometimes with blood
- • Tachycardia and tachypnoea
- • Calf swelling or pain (associated DVT)
- • Dizziness, syncope or shock in massive PE
Risk factors
- • Recent surgery, trauma or hospitalisation
- • Cancer
- • Pregnancy and postpartum period
- • Oestrogen therapy
- • Long-haul travel
- • Inherited thrombophilia
Causes
- • Embolised DVT (>90%)
- • Rarely: fat, amniotic fluid, air or tumour embolism
🚨 Red flags — seek urgent care
- • Sudden severe breathlessness, chest pain, collapse — call emergency services
- • Coughing up blood
- • Cyanosis, hypotension or loss of consciousness — massive PE
When to seek care
- • Any sudden breathlessness or pleuritic chest pain — emergency
- • Unexplained tachycardia with risk factors
Diagnosis
- • Wells / PERC score for probability
- • Age-adjusted D-dimer in low-probability cases
- • CT pulmonary angiogram is the standard confirmatory test
- • V/Q scan if CTPA contraindicated (renal impairment, pregnancy)
- • Echocardiogram for haemodynamic assessment
Treatment
- • Anticoagulation — DOAC for most haemodynamically stable PE
- • Systemic thrombolysis for massive PE with shock
- • Catheter-directed thrombolysis or embolectomy in selected high-risk cases
- • Oxygen, fluids and circulatory support as needed
- • Treat for ≥3 months; longer if unprovoked or persistent risk
Prevention
- • VTE risk assessment and thromboprophylaxis in hospital and after surgery
- • Mobilisation, hydration and compression on long journeys
- • Address modifiable risk factors (obesity, smoking, oestrogen)
Complications
- • Cardiovascular collapse and sudden death
- • Chronic thromboembolic pulmonary hypertension (CTEPH)
- • Right heart failure
- • Bleeding from anticoagulation
Prognosis
Mortality of treated stable PE is around 1–3%; massive PE carries 30%+ mortality. Most survivors regain near-normal function; a minority develop chronic pulmonary hypertension.
Education & self-care
PE is a treatable emergency. Sudden breathlessness with chest pain — especially after surgery, immobility or a leg DVT — needs immediate medical assessment.
Frequently asked questions
Can a PE be silent?
Small PEs may cause minimal symptoms but still carry risk of recurrence and chronic pulmonary hypertension.
How long will I need blood thinners?
Minimum 3 months; lifelong if PE was unprovoked, recurrent, or linked to ongoing risk such as cancer.
How is PE diagnosed?
A combination of clinical probability score (Wells), D-dimer blood test and CT pulmonary angiography. V/Q scanning is used in pregnancy or contrast allergy.
How long do I need anticoagulation?
At least 3 months. Unprovoked PE often requires longer-term anticoagulation, balanced against bleeding risk; cancer-associated PE is treated for as long as the cancer is active.
Can I fly after a PE?
Most people can fly safely after anticoagulation has been established for a few weeks, with hydration, regular movement and compression stockings on longer flights.