Blood clots sound scary—and they can be.

Even though blood clotting (or “coagulation”) can protect us by helping to prevent excessive bleeding in our bodies, it can be dangerous—or even deadly—if everything isn’t working properly.

How much do you know about blood clots and clotting-related conditions such as deep vein thrombosis (DVT) and pulmonary embolism (PE)? Take this quiz and find out…

Blood clots can:

Blood clots stop injured blood vessels from bleeding too much, but excessive clotting can block blood vessels that are not bleeding. Thankfully, our bodies have control mechanisms that, when working properly, limit clotting and dissolve any clots that are no longer needed. However, a problem with any of the control mechanisms (as occurs with the bleeding disorder hemophilia) can lead to too much bleeding…or too much clotting (as occurs in some people with diabetes). When clots clog small blood vessels in the brain, for example, a stroke can occur, while a blockage in vessels leading to the heart can cause a heart attack.

Deep vein thrombosis (DVT) is a blood clot that forms in a deep vein in your body. Which of the following symptoms are most likely to indicate a DVT?

About half of people with DVT have no symptoms at all. When symptoms do occur, the most common are swelling, pain, tenderness and redness of the skin at the site. Headache, tingling and itching are typically not associated with a blood clot of this kind. Although DVTs usually develop in a lower leg, thigh or the pelvis, they can also occur in an arm. If you have symptoms of DVT, contact your doctor immediately.

A pulmonary embolism (PE) is a blood clot that blocks a major artery in the lungs. Which of the following symptoms might indicate a PE?

Difficulty breathing, chest pain and light-headedness can all be symptoms of a PE. A PE can also cause faster-than-normal or irregular heartbeat, anxiety, coughing up blood, very low blood pressure or fainting. If you have any of these symptoms, you should seek emergency medical care immediately.


How many people develop DVT and/or PE each year?

The exact number is unknown, but it’s been estimated that 1 to 2 people in 1,000 are affected each year in the US. That’s about 900,000 people.

What increases your risk of developing a DVT?

Pregnancy can increase your risk for DVT—from four-fold to 20-fold during the weeks immediately following childbirth to 100-fold during the first week after the baby is born. Other conditions that raise risk for DVT include hospitalization for a medical illness (blood clots occur in up to 40% of medical and general surgery patients, even for a short-term stay), recent major surgery or injury, personal or family history of DVT, cancer and cancer treatments, hormone replacement therapy or birth control products. Additional risk factors include extended bed rest, obesity, smoking and prolonged sitting when traveling (longer than six to eight hours).

To help prevent blood clots, you should:

For most people, exercise is the key to preventing blood clots because movement improves blood flow. In addition to a regular exercise program, you should move around as soon as possible after being confined to bed, and get up and walk around every two to three hours when sitting for long periods (such as on an airplane). Note: To help prevent blood clots, you should not cross your legs when sitting. Maintaining a healthy weight and not smoking also help prevent blood clots. If your doctor believes you are at high risk for blood clots, you may also be advised to wear compression stockings and/or take medication (anticoagulants).


Herbal supplements that can affect blood clotting include:

A number of herbs and dietary supplements can affect blood clotting. For this reason, it’s important for you to discuss the use of herbs and supplements with your doctor or pharmacist before trying them—especially if you take medication such as an anticoagulant or any drug with blood-thinning effects including nonsteroidal anti-inflammatory drugs (NSAIDs)—for example, aspirin, ibuprofen (Advil) or naproxen (Aleve). The American Society of Anesthesiologists recommends discontinuing all dietary supplements and herbs at least two weeks prior to any surgery.

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