Pulmonary embolism is a life-threatening medical emergency that occurs when a blood clot, most commonly from the deep veins of the legs, gets stuck in an artery in the lungs, blocking the flow of blood. Other less frequent sources of pulmonary embolism include a fat embolus, air bubbles, and a deep vein thrombosis in the upper body. The portions of the lung served by each blocked artery cant get blood and may die. Risk factors for pulmonary embolism include:

• Aging
• Obesity
• Smoking
• Pregnancy
• History of connective tissue diseases such as rheumatoid arthritis or lupus
• Extended periods of immobility (prolonged air travel or recovery following surgery)
• Hormone-related therapies, such as oral contraception or testosterone

Symptoms of pulmonary embolism include sudden shortness of breath, chest pain, coughing up bloody mucus, a feeling of anxiety, rapid or irregular heartbeat, lightheadedness or dizziness, excessive sweating, fever, leg pain or swelling, or both, usually in the back of the lower leg, and clammy or discolored skin. A pulmonary embolism can cause heart or lung damage and even death if not treated promptly.