What is Deep Vein Thrombosis?

Deep vein thrombosis (DVT) occurs when a blood clot forms in a vein, usually in the leg. Since blood in veins is returning to the lungs for oxygenation, the clot can be pushed into the lungs and cause a pulmonary embolism, which can result in partial or full restriction of blood supply to the lungs. Depending on the severity of the embolism, either stress on the heart and lungs or fatality can result.

Deep veins are attached to muscles, leading to the inferior and superior vena cavae. These two central veins represent the main collection source for all blood returning to the lungs. Since the vena cavae are rather large, it is easy for a clot from a smaller vein to quickly pass through them to create a pulmonary embolism. As such, deep vein thrombosis is a medically urgent condition.

Unfortunately, deep vein thrombosis can be completely asymptomatic in about half of the cases. If symptomatic, those afflicted may notice a feeling of warmth and a change in skin color. The leg may appear blue or red. Additionally, swelling and leg pain may be present. Pain may worsen when walking or standing.

Certain factors may increase the risk of developing deep vein thrombosis. Episodes of DVT most frequently occur in people who have had recent hip or cardiac surgery. High levels of platelets, which significantly increase blood clotting, can also create susceptibility, as can cancer.

Those on long flights are at a rare but increased risk, sometimes called "economy class" syndrome. Deep vein thrombosis is also a risk for people over 60, those taking birth control or hormone replacement therapy for menopause, pregnant women and those who have just given birth, and those who are obese. Having more than one risk factor increases the likelihood of experiencing DVT.

If deep vein thrombosis is suspected, a physician may run several tests to confirm diagnosis. Ultrasounds can sometimes spot a clot. A venography is another common diagnostic procedure. The physician injects dye into the veins and takes X-rays to see if the flow of dye has been stopped, indicating the presence of a clot.

Once diagnosed, there are several treatments for deep vein thrombosis. A physician may prescribe anticoagulants, either injected like heparin, or taken orally like warfarin, to reduce further clotting. Additional treatments can include placing a stent-like filter in the vena cavae to prevent clots from passing into the lungs. In very rare cases, surgery may need to be performed to remove excessively large pulmonary embolisms from the lungs, but generally pulmonary embolism can be resolved by the above treatments.

Recommendations for preventing deep vein thrombosis include wearing graduated compression stockings, which apply pressure to the legs. Elevating the legs and walking or standing every 30 minutes may additionally help reduce clotting. Those who have just had surgery are advised to attempt mobility as soon as possible for this reason. If one is taking a long flight, physicians recommend getting up and walking for a few minutes every couple of hours.