Chronic thrombosis is a blood clot in a deep vein that has lasted for at least a month. It can be difficult to treat and can lead to scarring and vein damage. Treatment may involve compression stockings, medication, and surgery.

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Thrombosis, also called deep vein thrombosis (DVT), is a condition that occurs when a blood clot develops in a deep vein. It most commonly occurs in leg veins.

Thrombosis is called chronic thrombosis when the clot lasts for at least a month. This is different from acute thrombosis, which involves clots that have developed only within the previous few weeks.

Chronic thrombosis clots often harden and become more attached to the walls of veins than acute thrombosis clots. This can make them more difficult to treat and can lead to valve and vein damage. Treatment options for chronic thrombosis include medications, compression stockings, and surgical procedures.

Learn more about thrombosis.

A blood clot that has formed in a deep vein and lasted for at least a month is called chronic thrombosis. Clots of this type harden and can then damage the vein walls and valves and cause scarring.

These clots can also cause the vein to become narrowed and make it more difficult for blood to flow through.

Chronic thrombosis doesn’t always cause symptoms. When symptoms occur, they can be similar to those of many other conditions. If you experience any symptoms that could be related to chronic thrombosis, it’s a good idea to make a medical appointment.

Symptoms that could indicate chronic thrombosis include:

Healthcare professionals might order the following tests to help them confirm a diagnosis of chronic thrombosis:

  • Duplex ultrasound: This type of ultrasound uses sound waves to create images of the blood vessels in your legs and determine the speed at which blood is flowing through them. It can help doctors find areas of narrowing and blockages and see how severe the blockages are.
  • Magnetic resonance imaging (MRI) scan: An MRI can capture detailed images of body tissues and veins. It can help healthcare professionals see any blockages in your veins, including blood clots.
  • D-dimer blood test: D-dimer is a protein found in clots, and most people who have thrombosis have high levels of it in their blood. Testing for it can help confirm a diagnosis.
  • Venography: Venography involves injecting a specialized dye into your veins to make them show up clearly on an X-ray. Healthcare professionals can use this method to get an accurate picture of all the veins in your leg.

There are several treatment options for chronic thrombosis. The right treatment option for you will depend on factors such as the location and severity of your clot, your overall health, any medications you’re taking, and how long you’ve had the clot.

Treatment options include:

  • Compression stockings: Compression stockings are tight-fitting knee-high socks that help blood flow through your lower legs. They reduce swelling and prevent your blood from pooling.
  • Blood-thinning medications: Blood thinners, sometimes called anticoagulants, are a class of medications that can prevent clot growth and reduce your risk of new clots.
  • Thrombolytic medications: Thrombolytics are sometimes called clot-busters. They destroy existing blood clots and are normally used for severe chronic thrombosis.
  • Catheterization surgery: During this procedure, a surgeon will insert a thin, flexible tube into your vein and gently guide it to the blood clot. They will then use small tools to treat the clot. They might insert a stent to open the vein wider or insert a filter that can catch any blood clots that break loose and prevent them from reaching your lungs.
  • Surgical clot removal: In some cases, healthcare professionals can surgically remove a clot with a procedure called a thrombectomy or embolectomy.

There are a few possible complications of chronic thrombosis. The most serious is a pulmonary embolism, which can occur when a piece of the clot breaks free and gets stuck in a blood vessel in your lungs. A pulmonary embolism can be fatal and is a medical emergency.

Other possible complications of chronic thrombosis include permanent leg damage and medication side effects.

Anyone can develop chronic thrombosis, but you might have a greater chance of developing the condition if you:

  • have obesity
  • are older than 60 years
  • cannot move around for long periods
  • have any health condition that affects blood clotting
  • are pregnant
  • have type A blood
  • have cancer
  • recently had surgery
  • use hormonal birth control
  • have a family history of any kind of blood clots

Chronic thrombosis is a serious condition but is typically treatable. If you have chronic thrombosis, it’s important to follow the treatment plan your doctor recommends and keep all follow-up appointments.

Depending on the severity of your clot and how your body responds to medications, you might need to take certain steps to manage the condition, such as continuing to wear compression stockings and take blood thinners for as long as a year.

Even once you stop or reduce use of blood thinners, your doctor might want you to have regular testing to make sure you have not developed a new clot.

Can you prevent chronic DVT?

Although there’s no way to fully guarantee prevention of chronic thrombosis, there are steps you can take to reduce your risk, including:

  • Keep moving: Even if you’re managing an illness or injury, the more you can move your legs, the more you can lower your risk.
  • Take time to stretch: It’s a good idea to stretch your legs often, especially during long trips in a plane, car, or train.
  • Seek support to quit smoking: Smoking is linked to an increased risk of clots.
  • Try to maintain a moderate weight: Obesity is linked to an increased risk of chronic thrombosis. By reaching or maintaining a healthy weight, you can help lower your risk.

Is thrombosis common?

Thrombosis is common, especially in people over 60 years old and people who are in hospitals or long-term care settings. It’s the third most common cause of death from vascular disease in the United States.

Is it safe to exercise if I have chronic thrombosis?

Yes, exercise is safe. But if you’re taking blood thinners, it’s best to avoid contact sports and other activities that could cause bleeding. Talk with your healthcare professional about the best types of exercise for you.

Chronic thrombosis occurs when a blood clot has been in a deep vein for more than a month. The clot can harden and attach to the vein walls. This makes treatment more difficult and can lead to scarring and vein narrowing.

Chronic thrombosis can have severe complications, including fatal pulmonary embolism, but treatment can reduce the risk of complications.

Treatment options typically include wearing compression stockings and taking blood-thinning medications. When chronic thrombosis is severe, additional treatments such as thrombolytics, catheterization surgery, and surgical clot removal may be necessary.