Overview

Deep vein thrombosis (also called DVT) occurs when a blood clot (thrombus) forms in the deep veins. This most often occurs in the legs. Veins are blood vessels that return blood to the heart.

The veins of the lower legs carry blood from the feet and legs back to the heart. Clots sometimes occur when blood return is slowed, such as when you are on a long airplane flight. When blood is slowed, it tends to pool and then clot. Also, some illnesses, medications and other factors increase your tendency to form clots. Smoking also increases your risk for having a DVT.

In some cases, you can prevent DVT by getting more exercise, taking medications as directed and other measures.

Clots in the deep veins are dangerous. They can become dislodged and travel to the heart and then the lungs. If this happens, the clot can block blood flow to the lungs. This is called a pulmonary embolism and it can be fatal.

It is important to know the symptoms of DVT so you can seek treatment. Usually, DVT is treated with medication to keep clots from getting larger or breaking loose and traveling to the lungs.