Blood clots in the lungs, also known as pulmonary embolism, occur when a blood clot gets stuck in an artery in the lungs, blocking the flow of blood. Most blood clots that cause pulmonary embolism are formed in the deep veins of the legs, a condition known as deep vein thrombosis (DVT) . The blood clot most often starts in a deep vein in the leg and travels to the lung. However, blood clots can also form in the deep veins of the arms or pelvis. Other factors that can increase the risk of blood clots and pulmonary embolism include:

• Blood thats more likely to clot, which can be caused by medications like birth control pills, smoking, cancer, recent surgery, or pregnancy.
• Not moving for a long time or having changes in normal blood flow, which can happen if youve been in the hospital or on bed rest for a long period of time, or during a long flight or vehicle ride.
• Injury to the blood vessel wall, which can be caused by injury to your lower leg or a big bone break.
• Genetic conditions that increase the risk of blood clot formation.
• Certain autoimmune diseases or a family history of blood clots.

Its important to note that pulmonary embolism can be life-threatening, and about one-third of people with an undiagnosed and untreated pulmonary embolism dont survive. If you suspect you have a blood clot in your lungs, seek medical attention immediately.