Acute Pulmonary Embolism

A pulmonary embolism (PE) is a blood clot that travels through the bloodstream and lodges in one of the pulmonary arteries, the blood vessels that carry blood from the heart to the lungs. Most clots that cause a PE begin as a deep vein thrombosis (DVT) in a leg or pelvic vein and break loose, traveling through the veins, the right side of the heart, and into the lungs.

The most common symptoms are sudden shortness of breath, sharp chest pain that often worsens with a deep breath, a rapid heart rate, and sometimes a cough that may bring up blood-streaked sputum. More severe presentations can include fainting, lightheadedness, and low blood pressure. Leg swelling, pain, or redness, suggesting a deep vein thrombosis, sometimes accompanies these symptoms. Any of these, especially in combination or in someone with a known risk factor, warrants prompt medical evaluation.

Evaluation typically starts with an assessment of how clinically likely a PE is, using a validated tool such as the Wells score, together with your history and exam. If probability is low or intermediate, a D-dimer blood test is often used first, since a normal D-dimer makes PE unlikely enough to reasonably rule it out without imaging in that setting. When imaging is needed, CT pulmonary angiography (CTPA) is the standard test used to directly visualize a clot in the pulmonary arteries. A ventilation-perfusion (V/Q) scan is used instead of CTPA in specific situations, such as significant kidney impairment, a contrast allergy, or pregnancy.

D-dimer is a blood test that detects a breakdown product of clot formation. It is very sensitive, meaning a normal result makes a clot unlikely, which is why it's useful for ruling PE out in patients with low or intermediate clinical probability. However, it is not very specific: many conditions besides PE, including recent surgery, pregnancy, infection, and cancer, can also raise D-dimer, so an elevated result does not confirm a PE and generally leads to imaging rather than a diagnosis on its own.

A 2026 multi-society guideline introduced a five-level Clinical Category system, A through E, that replaces the older, less precise "massive, submassive, and low-risk" language. The categories run from a subclinical, incidentally found clot with no symptoms at the low end, through symptomatic PE with favorable risk-score findings, to categories reflecting right heart strain and abnormal biomarkers, up to the most severe category involving shock or cardiac arrest. The goal is to match the intensity of monitoring and treatment, from safe outpatient management to hospitalization and advanced therapies, to a patient's actual risk rather than a binary label.

No. Severity varies enormously. Some pulmonary emboli are small, incidental findings on imaging done for another reason, with no meaningful symptoms and a favorable outlook with anticoagulation alone. Others cause significant strain on the heart or, in the most severe cases, shock, which is a genuine medical emergency. This wide range is exactly why current guidance sorts confirmed PE into distinct severity categories rather than treating every diagnosis identically.

Anticoagulation, blood-thinning medication, is the foundation of treatment for nearly everyone with a confirmed PE. Current guidance generally favors a direct oral anticoagulant (DOAC) over warfarin for most patients, given a lower associated bleeding risk. The most severe presentations, particularly those involving shock, may require thrombolytic ("clot-busting") medication or a catheter-based procedure to more rapidly reduce clot burden, decisions made in the hospital by a coordinated care team.

For most patients, current guidance favors direct oral anticoagulants (DOACs) over warfarin, largely because DOACs are associated with a lower risk of major bleeding, including intracranial hemorrhage, and don't require routine blood monitoring. There are important exceptions: pregnancy and antiphospholipid syndrome are generally managed with heparin or warfarin rather than a DOAC, since DOAC safety and effectiveness are not established in the same way for these situations.

Most patients are treated for at least 3 to 6 months. Whether anticoagulation continues beyond that depends on whether the PE was "provoked" by an identifiable, resolved trigger such as recent surgery, or "unprovoked," with no clear cause. Extended anticoagulation is generally favored after an unprovoked first PE or when an ongoing risk factor, such as active cancer, remains present, since the recurrence risk in those situations is meaningfully higher. This is an individualized decision revisited over time, weighing bleeding risk against recurrence risk.

Yes. Anyone who has had one venous thromboembolic event, whether a DVT or a PE, has an elevated risk of another compared with someone who has never had one. This risk is a central factor in deciding how long anticoagulation should continue and is part of why ongoing risk factors, such as active cancer or a persistent clotting disorder, are taken seriously in that decision.

Post-PE syndrome describes persistent breathlessness, reduced exercise tolerance, or fatigue that continues for months after an otherwise appropriately treated pulmonary embolism. It is a recognized pattern, not something to simply push through in silence, and it is also part of why persistent symptoms after PE treatment deserve follow-up, since a small proportion of patients with this pattern are found to have chronic thromboembolic pulmonary hypertension (CTEPH) rather than ordinary, expected recovery.

A deep vein thrombosis (DVT) is a blood clot within a deep vein, most often in the leg or pelvis. A pulmonary embolism (PE) occurs when part or all of that clot breaks loose and travels to the lungs, lodging in a pulmonary artery. The two are closely related parts of the same underlying process, venous thromboembolism (VTE), and a person can be diagnosed with either, or both together.

Yes. The clot that causes a PE begins in a deep vein in a meaningful proportion of cases without ever having been detected or symptomatic before it traveled to the lungs. A normal-feeling leg does not rule out that a DVT was, or still is, present.

Not automatically, but persistent, unexplained breathlessness or reduced exercise tolerance that continues for months after a treated pulmonary embolism is a specific reason to be evaluated for chronic thromboembolic pulmonary hypertension (CTEPH), since CTEPH is one of the few causes of pulmonary hypertension that can potentially be treated with a curative surgery when caught and referred appropriately.