A pulmonary embolus is a blockage of an artery in the lungs by fat, air, blood clot, or tumor cells.

Pulmonary emboli are most often caused by blood clots in the veins, especially veins in the legs or in the pelvis (hips). More rarely, air bubbles, fat droplets, amniotic fluid, or clumps of parasites or tumor cells may obstruct the pulmonary vessels.

The most common cause of a pulmonary embolism is a blood clot in the veins of the legs, called a deep vein thrombosis (DVT). Many clear up on their own, though some may cause severe illness or even death.

Risk factors for a pulmonary embolus include:

• Prolonged bed rest or inactivity (including long trips in planes, cars, or trains)
• Oral contraceptive use
• Surgery (especially pelvic surgery)
• Childbirth
• Massive trauma
• Burns
• Cancer
• Stroke
• Heart attack
• Heart surgery
• Fractures of the hips or femur

Persons with certain clotting disorders may also have a higher risk.

Symptoms of pulmonary embolism may be vague, or they may resemble symptoms associated with other diseases. Symptoms can include:

• Cough
  • Begins suddenly
  • May produce bloody sputum (significant amounts of visible blood or lightly blood streaked sputum)
• Sudden onset of shortness of breath at rest or with exertion
• Splinting of ribs with breathing (bending over or holding the chest)
• Chest pain
  • Under the breastbone or on one side
  • Especially sharp or stabbing; also may be burning, aching or dull, heavy sensation
  • May be worsened by breathing deeply, coughing, eating, bending, or stooping
• Rapid breathing
• Rapid heart rate (tachycardia)

• Wheezing
• Clammy skin
• Bluish skin discoloration
• Nasal flaring
• Pelvis pain
• Leg pain in one or both legs
• Swelling in the legs (lower extremities)
• Lump associated with a vein near the surface of the body (superficial vein), may be painful
• Low blood pressure
• Weak or absent pulse
• Lightheadedness or fainting
• Dizziness
• Sweating
• Anxiety

Tests to evaluate the function of the lungs:

• Arterial blood gases
• Pulse oximetry

Tests to detect the location and extent of embolism:

• Chest x-ray
• Pulmonary ventilation/perfusion scan
• Pulmonary angiogram
• CT angiogram of the chest

Tests to detect DVT:

• Doppler ultrasound exam of an extremity blood flow studies
• Venography of the legs
• Plethysmography of the legs

An ECG may show abnormalities caused by strain on the heart.

This disease may also alter the results of the following tests:

• Echocardiogram
• D-dimer level
• Chest CT scan
• Chest MRI scan