Basilic vein thrombosis is a type of superficial venous thrombosis (SVT) in which a blood clot forms in the basilic vein in the arm. In many cases, SVT is harmless and will resolve without treatment.

The basilic vein extends from the palm along the ulna bone of the forearm on the same side as the little finger. The vein is superficial, which means it is below the skin’s surface rather than below layers of tissue and muscle.

Thrombosis in a superficial vein, such as the basilic vein, differs from deep vein thrombosis (DVT). Doctors do not typically consider SVT to be a serious condition, although it may lead to complications in some people.

This article looks at the symptoms, causes, diagnosis, and treatment for basilic vein thrombosis. It also looks at possible complications, how to help prevent the condition, and its outlook.

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The symptoms of basilic vein thrombosis occur in the arm, and a person may experience the following at the site of the basilic vein:

  • discoloration
  • warmth
  • tenderness
  • swelling
  • hardening of the vein, which can feel similar to a knot or cord

Someone who experiences symptoms of SVT in the basilic vein should contact a doctor. This is because the condition may indicate a more severe type of thrombosis, such as DVT.

DVT in an arm can lead to severe complications, such as a blood clot dislodging and traveling to the lungs. This can result in pulmonary embolism, which can be life threatening.

A blood clot may develop in the basilic vein for various reasons.

Researchers and doctors associate the development of blood clots in the superficial veins with several conditions and factors, including:

To diagnose basilic vein thrombosis, a doctor may physically examine the affected arm, ask questions about a person’s symptoms and medical history, and order an ultrasound.

To perform the ultrasound, a technician will move a handheld ultrasound probe along the basilic vein. The probe uses sound waves to create images of the vein for the technician to view on a screen.

The technician will push down the vein to see whether it collapses as it should or resists. If a blood clot is present, the vein will not collapse.

The treatment for basilic vein thrombosis will likely depend on the severity of the condition.

SVT often resolves on its own. Treatment to relieve mild symptoms may include:

  • using a warm compress
  • taking anti-inflammatory medications such as ibuprofen
  • raising the arm above the heart to reduce swelling
  • using a compression bandage

If a person has severe symptoms or a doctor believes there is a risk of the blood clot extending into the deep veins, treatment can include anticoagulant medications. A person may take these orally, or a doctor may inject an anticoagulant, such as fondaparinux (Arixtra).

Learn more about treatments for SVT.

DVT and pulmonary embolism are major potential complications of blood clots in superficial veins.

According to research, the risk of SVT progressing to DVT or pulmonary embolism is lower when it occurs in the upper extremities, as with the basilic vein, compared with the lower extremities. Although it is rare for thrombosis in the basilic vein to progress to DVT and pulmonary embolism, doctors have reported cases.

A pulmonary embolism is a severe condition that can be life threatening. A person should contact a doctor if they have symptoms of DVT, which may lead to pulmonary embolism. These include symptoms at the site of the vein, such as:

  • swelling
  • throbbing pain
  • darkened or discolored skin
  • warmth
  • hard, swollen veins that are painful to the touch

Learn about the different types of pulmonary embolism.

Steps a person can take to help prevent thrombosis in the basilic vein, and SVT in general, include:

  • using compression bandages
  • avoiding injury to varicose veins
  • taking any prescribed anticoagulation medications, especially following surgery
  • exercising regularly
  • maintaining a moderate weight

The outlook for basilic vein thrombosis can depend on the condition’s underlying cause.

In general, the outlook for SVT is positive. For cases with a high risk of complications or more severe SVT, the outlook is typically good with appropriate treatment.

DVT occurs in 6–36% of people with SVT, and pulmonary embolism in 2–13%. Although the risk of progression to DVT is lower in basilic vein thrombosis than in the lower extremities, it remains a possible complication.

Basilic vein thrombosis is a type of SVT in which a blood clot forms in the arm’s basilic vein. SVT occurs in veins under the skin rather than deep veins under layers of tissue and muscle.

Basilic vein thrombosis and other SVTs are typically harmless and may resolve without treatment. They differ from more severe DVTs, which can lead to severe complications such as pulmonary embolism.

A person should contact a doctor if they have symptoms of basilic vein thrombosis or SVT in another area, as there are links between SVTs and DVTs.