• Cardiovascular

    TUESDAY Q & A: Variety of factors can raise risk for deep vein thrombosis (DVT)

DEAR MAYO CLINIC: My mother has had deep vein thrombosis twice. I’ve heard this condition can run in families. I’m a 38-year-old woman in good health. I exercise regularly and eat well. What can I do to lower my risk of developing DVT?Deep Vein Thrombosis Illustration

ANSWER: Deep vein thrombosis (DVT), happens when a blood clot forms in a vein located deep within the leg or pelvis. It is a serious condition because if the clot breaks free and travels to your lungs, it can be life-threatening. A variety of factors can raise your risk for these blood clots, including a family history of DVT, as well as recent surgery, hospitalization for a medical illness, trauma with or without fracture, obesity, immobility, and certain drugs.

DVT most often happens in the large veins within the legs. If a clot in a vein comes loose, it can be carried through your body in the blood flowing back to your heart. From there, it may be pumped into your lungs. A clot that gets stuck in a blood vessel within the lungs — a condition known as a pulmonary embolism — causes sudden death in about 20 to 25 percent of cases.

As a young person in good health, your chances of developing DVT are low. But, as you mention, the fact that someone in your family has had DVT does raise your risk. There are a number of steps you can take to reduce your risk.

Keep exercising and eating well to maintain a healthy weight. Being overweight or obese puts extra pressure on the veins in your pelvis and legs, raising the risk that a blood clot could develop. If you smoke, stop. If you don’t smoke, don’t start. Smoking affects your blood circulation and clotting.

Traveling long distances, especially on an airplane where you cannot move around much, can be a risk factor, too. That’s because when your legs are still for long periods of time, your calf muscles do not contract, which usually helps the blood in your legs to circulate properly. The same problem can happen if you need to be on prolonged bed rest.

To lower your risk while traveling, take a walk around the airplane once every hour on long flights. If you are driving, stop every few hours and walk around the car a few times.  Move your feet up and down and rotate your ankles.

Your DVT risk also may go up if you have major surgery. Surgery can slow your blood flow, and general anesthetics used during surgery temporarily widen your veins. Both can increase the chances of blood pooling and clotting in your veins. If you need surgery or if you are hospitalized, make sure your health care team knows about your family history of DVT. You may be given small doses of a blood thinner to help prevent blood clots.

Your chance of developing DVT also goes up if you become pregnant, since pregnancy increases the pressure in the veins in your pelvis and legs. The risk of blood clots from pregnancy can continue for up to six weeks after you give birth. Talk to your health care team about possible DVT if you become pregnant.

Birth control pills or hormone replacement therapy can have an effect on your blood’s ability to clot, and that may raise your risk of DVT. If you are taking these drugs, talk to your doctor to see if an alternative might be appropriate.

Even if you take all these steps, it is still important for you to be able to recognize the symptoms of DVT. If you have leg pain or swelling, particularly below the knee in your calf muscle, ankle or foot; if your leg is warm to the touch, tender, red or inflamed; or if you develop chest pain or shortness of breath, seek medical attention immediately. John Heit, M.D., Cardiovascular Diseases, Mayo Clinic, Rochester, Minn.