A pulmonary embolism is a serious medical problem. In fact, it can be a life-threatening emergency. Check the answers to these frequently asked questions to find out if you're at risk, how to prevent a pulmonary embolism, and how to spot one. What is a pulmonary embolism? A pulmonary embolism is a sudden blockage of the blood flow to one of the arteries in your lungs. This keeps your lungs from getting the blood they need. Any kind of substance can cause a blockage. Almost always, though, it's a blood clot. One or several clots can cause a pulmonary embolism. The clots may be very large or very small. How does a pulmonary embolism come about? A pulmonary embolism occurs when a blood clot travels from another part of your body to your lungs. It can get stuck and then suddenly cuts off needed blood supply. A blood clot that develops in one area and moves through the bloodstream is an embolus. Most often, a clot that causes a pulmonary embolism formed in a vein deep within the body. That's usually in the legs. The name for this kind of clot is a deep vein thrombosis (DVT). Am I at risk? There are several known risk factors for pulmonary embolism. You're at risk if you: Have heart disease, especially heart failure Recently had surgery Have lung, ovarian or pancreatic cancer or any metastatic cancer, among others Have chemotherapy for cancer Have a family member who's had a pulmonary embolism or DVT Stay in one position for a long time, like on a long flight Smoke Are pregnant Take estrogen Are obese What are the warning signs of a pulmonary embolism? The symptoms of pulmonary embolism vary from person to person. They depend on where in your lung the blockage is. They also vary by the size of the blockage. Coughing a lot, especially coughing up blood, is a common symptom. Sharp chest pain is another warning sign. Be aware of pain that gets worse when you: Take a deep breath Bend over Eat Cough Exercise (and doesn't stop when you rest) There's more to watch for. You might have swelling in one of your lower legs. You may also have pain in the leg, and it may be red and feel warm. Clammy skin, changes in skin color, and feeling dizzy are other warning signs. You may sweat heavily and have a fever. Your heart may beat very quickly or in an abnormal pattern. Pulmonary embolism can be fatal. It's important to go to an emergency room for treatment immediately if you have symptoms of a pulmonary embolism. How is it diagnosed? Your doctor will ask about your symptoms, your medical history, and your family’s medical history. You may have tests like X-rays, blood tests, or an ultrasound. There are also more advanced tests: Spiral CT (computed tomography) uses a special scanner that moves around your body and creates a picture of your lungs. This helps your doctor see the embolism. VQ (ventilation/perfusion) scan shows where there might be problems with the flow of air and blood in your lungs. Pulmonary angiogram is a specialized X-ray. Your doctor puts a thin tube into an artery and injects a dye that makes it easier to see an embolism with X-rays. This test has become less common today. How do doctors treat a pulmonary embolism? Doctors usually prescribe medication to treat a pulmonary embolism, typically a blood thinner. This drug helps keep more clots from forming. It also can keep an existing clot from growing. If a clot is causing a life-threatening blockage, you may take a drug that can break it up. A common name for them is clot-busting drugs. Or, your doctor may put a thin tube (catheter) into a vein and use it to break up the clot. Some people need surgery to remove a clot, but this is rare. Can I prevent a pulmonary embolism? You can take steps to keep blood clots from forming in your deep veins. These steps are very important after any surgery. First, be sure to take the blood thinner if your doctor prescribes it. You also may need to prop up your legs and wear compression stockings that encourage blood flow in your legs. Get up and walk around as soon as possible after surgery. If you're taking a long trip by car or plane, stretch your legs and move around as often as possible. This will help prevent blood clots. If you’re concerned about DVT and pulmonary embolism or think you are at risk, talk with your doctor about your specific risk factors and ways to reduce your risk.