About Blood Clots

On this page:

What are Blood Clots?

Who is at risk for blood clots?

What are the symptoms of a blood clot?

How can blood clots be prevented?

What are Blood Clots?

A blood clot is formed when blood clumps together. This is a normal protective mechanism to stop excessive bleeding when the body suffers a cut or wound. When a blood clot forms inside a blood vessel of the body, however, the result can be serious harm or death.

Deep vein thrombosis (DVT) is a blood clot in a deep vein, most commonly in the lower leg or thigh. The clot can block blood flow and cause pain, swelling, and skin discoloration. A blood clot that forms in a deep vein can become dislodged and travel through the bloodstream. This is called an embolus. Pulmonary embolism (PE) is the condition that results when a clot that has been dislodged travels to the lung.

Who is at risk for blood clots?

Most blood clots occur in persons with risk factors for development of a blood clot. The risk increases even more for someone who has more than one risk factor at the same time.

Factors that increase risk are:

  • Age: those aged 65 or older are more likely to develop deep vein thrombosis
  • Smoking
  • Being overweight and obesity
  • Varicose veins (enlarged veins, often found in the legs)
  • Cancer and its treatment
  • Recent surgery or broken hip, pelvis, or leg
  • A bad bump or bruise, such as following a fall
  • Being confined to a bed or chair much of the time
  • Travel on long trips, especially longer than four hours confined in a car, plane, etc.
  • In women, use of hormones for menopause or birth control
  • Ethnicity: African Americans and Caucasianss are more likely than other groups to develop deep vein thrombosis
  • Certain inherited blood disorders or factors that make your blood thicker or more likely to clot as well as a family history or previous deep vein thrombosis or pulmonary embolism
  • Pregnancy and childbirth

What are the symptoms of a blood clot?

Only about half of people with deep vein thrombosis have symptoms. These symptoms usually occur in the leg affected by the deep vein clot. They include:

  • Swelling of the leg or along a vein in the leg
  • Pain or tenderness in the leg, which you may feel only when standing or walking
  • Increased warmth in the area of the leg that's swollen or in pain
  • Red or discolored skin on the leg

Some people don't know they have DVT until they have signs or symptoms of pulmonary embolism. Symptoms of PE include:

  • Unexplained shortness of breath, or having a hard time breathing
  • Fainting spells
  • Pain with deep breathing
  • A cough, with or without blood

Rapid breathing and a fast heart rate also may be signs of PE.

How can blood clots be prevented?

If you have one or more risk factors for blood clots, the steps listed below may be especially helpful in reducing your risk of developing a blood clot.

General practices:

  • Wear loose-fitting clothes, socks, or stockings
  • Wear special stockings (called compression stockings) if your doctor prescribes them
  • See your doctor for regular checkups and take all the medicine your doctor prescribes
  • Do not stand or sit for more than 1 hour at a time
  • Do not use pillows under your knees

When traveling:

  • Walk up and down the aisles of the bus, train, or airplane; if traveling by car, stop about every hour and walk around
  • Move your legs and flex and stretch your feet to encourage blood flow in your calves
  • Wear loose and comfortable clothing
  • Drink plenty of fluids and avoid alcohol

When in the hospital:

  • For elective surgery, such as a joint replacement, ask your doctor about blood clot prevention when you are planning the surgery
  • For an unplanned hospital stay, such as a broken hip or prolonged medical illness, ask your doctor if you need compression stockings or medication to prevent a blood clot
  • Get out of bed and move around as soon as possible after surgery or illness, to lower your chance of developing a blood clot