Deep Vein Thrombosis - What Happens

What Happens

If you have symptoms of deep vein thrombosis, testing will begin immediately to determine whether you have a blood clot in your leg.

Often people with deep vein thrombosis do not have any symptoms. In these people, this condition is usually suspected only after a blood clot is discovered in the lung (pulmonary embolism). Typically, the blood clot in the lung came from a deep vein clot in the leg that was not causing symptoms.

When you are diagnosed with deep vein thrombosis, treatment begins if it is likely that the blood clot will grow or that a piece of the clot might break loose and flow to the lungs (pulmonary embolism). If you have a blood clot in your upper (proximal) leg vein, you will likely need to take anticoagulant medicine for 3 to 6 months, and possibly longer.¹

After 3 to 6 months, your doctor may recommend that you continue warfarin (such as Coumadin) on an ongoing basis to prevent deep vein clots from recurring.²

Typically, if you have a blood clot in the lower (distal) deep leg veins, you will need to take medicine to prevent more blood clots (anticoagulant medicine) for about 3 to 6 months. The length of time will vary based on your own health. Sometimes your doctor will not start this medicine right away. He or she will wait 24 to 48 hours to see if your blood clot is growing. For symptom relief, your doctor may recommend a nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen.

The main goal of treatment is to prevent the blood clot from growing or moving to the lungs. If a blood clot in the deep veins of the leg breaks loose, it can travel to the lungs and block blood flow (pulmonary embolism). Pulmonary embolism occurs in 25% of cases of untreated, diagnosed deep leg vein thromboses.³ In people who receive treatment for deep vein thrombosis, the rate of pulmonary embolism falls drastically. For more information, see the topic Pulmonary Embolism.

Blood clots in the lung (pulmonary emboli) occur more often in people with deep vein blood clots in the upper rather than the lower leg veins. Only about 25% of blood clots in the veins of the calf will become larger and extend into the upper leg or groin veins.⁴ Blood clots that extend into the upper leg veins usually require treatment with anticoagulant medicine to prevent pulmonary embolism.

The recurrence rate for deep vein thrombosis varies depending on what caused the blood clot and how it was treated. Recurrence is most common in people who have continuing risk factors (such as cancer or inherited blood-clotting problems) and in people who have had more than one blood clot in the leg. Recurrence is lowest in people who have a short-term risk factor, such as surgery or temporary inactivity.

In about 25% of people who have had deep vein thrombosis with symptoms, a condition called postthrombotic syndrome may develop.⁴ This condition can cause pain, swelling, discoloration, and sores on the leg. Postthrombotic syndrome usually develops within 2 years of the original blood clot.⁴ One study showed that compression stockings can cut your chance of developing postthrombotic syndrome nearly in half.⁵