What Is Thrombophlebitis?

Thrombophlebitis occurs mostly in the legs. It's a circulatory problem that develops when a blood clot slows the circulation in a vein, either right under the skin or deeper in the leg.

The name gives you a hint about what it is: "thrombo" means clot, and "phlebitis" means a vein with inflammation, or the swelling and irritation that happens as the result of an injury.

With thrombophlebitis (pronounced thrahm-bow-fleh-bye-tis), a blocked vein in the leg may become swollen, irritated, and even hard to the touch. Most cases involving the shallow leg veins begin to resolve by themselves in a week or two. But in rare occasions, these blocked veins can lead to infection and tissue damage from the loss of healthy circulation. 

When the deeper veins in the leg are involved, there are greater risks. A portion of the clot can break off and enter the bloodstream, travel far from the site where it formed and cause serious problems. If the clot reaches the lungs and blocks circulation there, it can even cause death. Blood thinners are usually started if there are blood clots in the deep veins. In the more serious cases, people with thrombophlebitis may need to be treated with drugs to "melt" the clot, lessen the swelling, or treat any infection that may develop.

What Causes Thrombophlebitis?

First, a blood clot forms, which can result from several causes -- most commonly from blood not moving the way it should through the leg veins. You could be sitting down for a long time in a place where you can't stretch out your legs, such as sitting on a long drive or airline flight. When blood sits still, it's more likely to form clots. Clots can also occur with extensive bed rest after a major illness or surgery. 

Varicose veins can cause thrombophlebitis as well. The blood vessels are stretched out too much, allowing blood to pool in the vessel instead of streaming straight through in one direction, which can lead to blood clots.

People also can develop thrombophlebitis as a complication of intravenous tubes, or IVs. Hospital staffers try to lower this risk by changing the spots where IV lines are placed in the body, but thrombophlebitis still is possible. Pregnant women may also develop thrombophlebitis before or shortly after the baby is born.

Other risk factors include certain cancers, use of the hormone estrogen for birth control or hormone replacement, age over 60, obesity, smoking, and a personal or family history of blood clots.