In short
A pulmonary embolism is a blood clot blocking part of the lung's blood supply, usually after traveling from a leg vein — and unlike most conditions in this library, its warning signs themselves are the reason to call emergency services, not just a doctor.
Emergency if: Any degree of sudden shortness of breath, sharp chest pain that worsens with breathing, a racing heart, fainting, or coughing up blood — call emergency services immediately. There is no mild version of these symptoms that's safe to wait out.
On your report
D-dimer
On this page
01
How a Clot Gets to the Lung
A pulmonary embolism, or PE, happens when a blood clot — almost always one that formed in a deep vein, usually in the leg (a deep vein thrombosis) — breaks loose and travels through the bloodstream to lodge in an artery in the lung, blocking blood flow to that part of the lung. The same risk factors that cause DVT apply here: prolonged immobility, recent surgery or hospitalization, cancer, pregnancy or estrogen-containing medications, smoking, and inherited clotting disorders.
How serious a PE is depends heavily on its size and location and how much it strains the heart, which has to pump against the new blockage — a small PE can cause mild symptoms, while a large one can be immediately life-threatening.
02
Recognizing It
Sudden shortness of breath is the most common symptom, often with chest pain that's sharp and worsens with a deep breath, a rapid heartbeat, and sometimes a cough (occasionally bringing up blood-tinged mucus) or lightheadedness. Symptoms can come on abruptly, over minutes, rather than building gradually.
Unlike many of the conditions covered here, there's no 'mild version to watch and wait on' — any of these symptoms, especially in someone with a known DVT or other risk factors, warrants immediate emergency evaluation, because a PE can worsen suddenly and there's no reliable way to tell a small one from a large one by symptoms alone.
03
How It's Diagnosed
In the emergency department, a D-dimer blood test can help rule out a PE in someone with a low likelihood based on symptoms and risk factors, but the definitive test is a CT scan of the chest with contrast dye (CT pulmonary angiography), which directly shows a clot in the lung's blood vessels. When contrast dye can't be used, a ventilation-perfusion (V/Q) scan is an alternative.
An echocardiogram (heart ultrasound) is often done as well to check whether the clot is straining the heart's right side, which affects how aggressively the PE needs to be treated.
04
Treatment
Blood-thinning medication (anticoagulation), started immediately, is the core treatment for most PEs, preventing the clot from growing while the body gradually dissolves it over weeks to months — similar to DVT treatment, since they're really the same underlying process in two locations.
For a large PE causing significant strain on the heart or dangerously low blood pressure, clot-dissolving medication (thrombolytics) or a procedure to remove the clot directly may be used, since these more aggressive treatments carry their own bleeding risks and are reserved for the more severe cases. Ongoing anticoagulation typically continues for at least three months, sometimes longer or indefinitely depending on the cause.
05
After a PE
Most people recover well with treatment, though some notice reduced exercise tolerance or breathlessness for weeks to months afterward, which usually improves over time. A small number develop longer-term lung or heart effects from a large PE, which is part of why follow-up with a doctor after treatment matters.
Anyone who has had one PE or DVT has some increased risk of another, so understanding personal risk factors, following the prescribed anticoagulation course fully, and knowing the warning signs described above — for both DVT and PE — are the main things that help catch a recurrence early.
How urgent is it?
Same-day — call promptly
New one-sided leg swelling, warmth, or pain — a possible DVT that can go on to cause a PE. Get evaluated the same day, before lung symptoms have a chance to start.
Emergency — act now
Any degree of sudden shortness of breath, sharp chest pain that worsens with breathing, a racing heart, fainting, or coughing up blood — call emergency services immediately. There is no mild version of these symptoms that's safe to wait out.
Values mentioned in this story
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Sources
- Pulmonary Embolismmedlineplus.gov
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