Causes and Risk Factors
Clots form when blood flow slows, vessel walls are injured, or the blood clots more easily than normal. Common risk factors include:- Prolonged immobility: Long flights or car trips, bed rest, or recovery after surgery — especially hip, knee, or abdominal operations.
- Cancer and its treatment: Many cancers increase clotting tendency.
- Hormones: Estrogen-containing birth control, hormone therapy, and pregnancy raise clot risk.
- Inherited clotting disorders: Conditions such as the factor V Leiden mutation and other hypercoagulable states make clots more likely, particularly when combined with other risks.
- Other factors: Obesity, smoking, heart failure, and a previous DVT or PE.
Symptoms
Symptoms depend on the size of the clot and can appear suddenly:- Shortness of breath: Often abrupt and worse with exertion.
- Chest pain: Typically sharp and worse with a deep breath or cough.
- Rapid heart rate, lightheadedness, or fainting: Signs the heart is under strain.
- Cough: Sometimes with blood-streaked sputum.
- Leg swelling or pain: A warm, swollen calf may signal the DVT that produced the embolism.
When to Seek Immediate Care
Pulmonary embolism is a medical emergency. Call 911 or go to the nearest emergency department for sudden unexplained shortness of breath, chest pain with breathing, coughing up blood, or fainting.Diagnosis
Doctors combine a risk assessment with testing. A D-dimer blood test can help rule out clots in lower-risk patients, while a CT pulmonary angiogram — a contrast CT scan of the chest — is the standard imaging test. Ultrasound of the legs, an electrocardiogram, and an echocardiogram may also be used to find the source of the clot and assess strain on the heart.Treatment
Treatment prevents the clot from growing and stops new clots while the body dissolves the old one.- Anticoagulants (blood thinners): Direct oral anticoagulants such as apixaban, rivaroxaban, dabigatran, or edoxaban are used for most patients; warfarin with regular blood-test monitoring is an alternative, and injectable enoxaparin is often used in the hospital or during cancer treatment. Treatment usually lasts at least three months, and sometimes indefinitely if risk factors persist.
- Clot-dissolving therapy or procedures: Reserved for massive, life-threatening clots, when medication is delivered directly to the clot or the clot is removed with a catheter.
- Oxygen and monitoring: Many patients with smaller clots and stable vital signs can now be treated at home, while larger clots are observed in the hospital.