What is Deep Vein Thrombosis (DVT)?

Deep vein thrombosis, commonly referred to as "DVT", occurs when a blood clot, or thrombus, develops in the large veins of the legs or pelvic area. Some DVT’s may cause no pain, whereas others can be quite painful. With prompt diagnosis and treatment, the majority of DVT’s are not life threatening. However, a blood clot that forms in the invisible "deep veins" can be an immediate threat to your life, as compared to a clot that forms in the visible "superficial" veins, the ones beneath your skin. A clot that forms in the large, deep veins is more likely to break free and travel through the vein. It is then called an embolus. When an embolus travels from the legs or pelvic areas and lodges in a lung artery, the condition is known as a "pulmonary embolism," or PE, a potentially fatal condition if not immediately diagnosed and treated.

What are the causes of DVT?

Generally, a DVT is caused by a combination of two or three underlying conditions:

• slow or sluggish blood flow through a deep vein
• a tendency for a person’s blood to clot quickly
• irritation or inflammation of the inner lining of the vein.

There are a variety of settings in which this clotting process can occur. First, individuals on bed rest (such as during or after a surgical procedure or medical illness, such as heart attack or stroke), or confined and unable to walk (such as during prolonged air or car travel) are common settings. It can occur in certain families in whom there is a history of parents or siblings who have suffered from prior blood clots. It can also occur in individuals whom active cancer or its treatment may predispose the blood to clotting.

Having a recent major surgical procedure, especially a hip and knee orthopedic surgeries or those requiring prolonged bed rest, predispose the blood to clotting. Irritation or inflammation occurs when a leg vein is injured by a major accident or medical procedure.

Also, there are specific medical conditions that may increase your risk of developing a DVT via these three mechanisms, such as congestive heart failure, severe obesity, chronic respiratory failure, a history of smoking, varicose veins, pregnancy and estrogen treatment. If you are concerned that you may be at risk due to any of these conditions, please consult with your physician.

Why is deep vein thrombosis dangerous?

DVT is potentially life-threatening.   In it, blood clots form in the body’s deep veins, particularly veins in the legs.  Sometimes the clot breaks off, travels through the bloodstream, and obstructs a vessel in the lungs, restricting blood flow.   This condition is called pulmonary embolism.  This damages tissues and causes poor lung function, which can be fatal.

People who survive their first episode of DVT may have chronic swelling in their leg and pain from the blockage of blood flow through the vein.  This can reduce their ability to live a full, active life.   People who’ve had one DVT episode are also prone to have more.

How do I prevent DVT during air travel?

Studies in healthy people have shown that wearing “compression stockings” may help minimize the risk of developing DVT after long flights.  These stockings put pressure on leg muscles and help return blood flow from the legs to the heart.

People with cardiovascular disease and those at risk for clots in their legs may benefit from a single dose of heparin.  This drug prevents clots from forming and is effective in reducing the risk of DVT in high-risk patients.

Drinking extra water, walking if feasible and avoiding alcohol intake are also good advice.  These steps aren’t scientifically proven to prevent traveler’s thrombosis, but they’re common sense.