Pulmonary Embolism (Blood Clot in the Lung)

  • Medical Author:
    Benjamin Wedro, MD, FACEP, FAAEM

    Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

  • Medical Editor: George Schiffman, MD, FCCP
    George Schiffman, MD, FCCP

    George Schiffman, MD, FCCP

    Dr. Schiffman received his B.S. degree with High Honors in biology from Hobart College in 1976. He then moved to Chicago where he studied biochemistry at the University of Illinois, Chicago Circle. He attended Rush Medical College where he received his M.D. degree in 1982 and was elected to the Alpha Omega Alpha Medical Honor Society. He completed his Internal Medicine internship and residency at the University of California, Irvine.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Quick GuideDVT in Pictures: Symptoms of Deep Vein Thrombosis, Beyond Leg Pain and More

DVT in Pictures: Symptoms of Deep Vein Thrombosis, Beyond Leg Pain and More

How is pulmonary embolism diagnosed?

There always needs to be a high a level of suspicion that a pulmonary embolus may be the cause of chest pain or shortness of breath. The healthcare professional will take a history of the chest pain, including its characteristics, its onset, and any associated symptoms that may direct the diagnosis to pulmonary embolism. It may include asking questions about risk factors for deep vein thrombosis.

Physical examination will concentrate initially on the heart and lungs, since chest pain and shortness of breath may also be the major complaints for heart attack, pneumonia, pneumothorax (collapsed lung), dissection of an aortic aneurysm, among other conditions.

With pulmonary embolism, the chest examination is often normal, but if there is some associated inflammation on the surface of the lung (the pleura), a rub may be heard (pleura inflammation may cause friction which can be heard with a stethoscope). The surfaces of the lung and the inside of the chest wall are covered by a membrane (the pleura) that is full of nerve endings. When the pleura becomes inflamed, as can occur in pulmonary embolus, a sharp pain can result that is worsened by breathing, so-called pleurisy or pleuritic chest pain.

The physical examination may include examining an extremity, looking for signs of a DVT, including warmth, redness, tenderness, and swelling.

It is important to note, however, that the signs associated with deep vein thrombosis may be completely absent even in the presence of a clot. Again, risk factors for clotting must be taken into consideration when making an assessment.

PERC Rule for Pulmonary Embolus

Being able to assess a patient and determine the risk for pulmonary embolus is very useful, since many patients have chest pain and shortness of breath when seen in an emergency department, urgent care facility, or their health care professional's office or clinic.

The PERC rule suggests that in low risk patients, if the answer is no to the following questions, that the risk of pulmonary embolus is very low (less than 2%) and no further evaluation for pulmonary embolism is necessary or required:

  • Age greater than 50
  • Heart rate greater than 100
  • Oxygen saturation on room air less than 95%
  • Previous history of venous thromboembolism
  • Trauma or surgery within the last 4 weeks
  • Hemoptysis (coughing up blood)
  • Exogenous estrogen prescription
  • Unilateral leg swelling (only one leg involved)

If the answer is yes to any of these questions, then the diagnosis of pulmonary embolus still needs to be considered.

Medically Reviewed by a Doctor on 11/20/2015

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