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The Dangers of Blood Clots: Thrombophlebitis

June 10, 2008 - 7:30am
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The Dangers of Blood Clots: Thrombophlebitis

Some forms of thrombophlebitis can have no symptoms, yet this condition can be deadly. Many people are unaware they have it. Here's what you should know about this condition that generally occurs in people over the age of 40.

Let's start by breaking down this imposing word, thrombophlebitis:

  • Phlebitis is inflammation of a vein or veins.
  • Thrombosis is the formation of a blood clot or clots in the veins.

Clotting and inflammation in the veins can damage them permanently. A clot that breaks loose from the wall of the vein and flows through the veins to the lungs (called pulmonary embolism ) can be deadly.

Thrombophlebitis, which is generally found in the legs, occurs in two forms— superficial vein thrombosis (SVT) and deep vein thrombosis (DVT). Superficial veins are close to the skin (surface veins) and deep veins are embedded in the muscles.

Superficial Vein Thrombosis

Superficial vein thrombophlebitis is an inflammation of the surface veins, and almost always occurs in the legs. Usually this inflammation is accompanied by tiny blood clots that cling to the interior lining of the veins. Though often painful, SVT itself generally presents no serious medical danger, but it may be a sign that a person has DVT elsewhere in the leg.

Below are some SVT symptoms:

  • A vein that is visible through the skin and feels hard and painful to the touch.
  • Redness, tenderness, and pain on the skin of the affected area.
  • A sensation of throbbing or burning just below the surface of the skin.
  • A pain or heavy feeling when lowering your leg.

The factors causing SVT can be numerous:

  • A blow, fracture, or other injury to the leg.
  • Prolonged bed rest, especially after surgery (which causes the blood to "pool" in the legs).
  • Varicose veins
  • Prolonged inactivity such as sitting in one position for extended periods of time (as on long car, train, or plane trips).
  • Smoking
  • Vein injuries caused by injections or intravenous needles.
  • Pregnancy
  • Obesity
  • Cancer

SVT can be treated with anti-inflammatory medication such as ibuprofen or aspirin usually taken for five to seven days, application of hot, moist compresses (20 minutes on, 20 minutes off), and elevation of the affected limb above the level of the heart until the pain and swelling dissipate. In addition, moving the legs is very important. People with a history of DVT or other vein thrombosis may need to take anticoagulant drugs (eg, Heparin).

"Although thrombophlebitis isolated to the superficial veins is not dangerous, occasionally it can migrate to the deep veins," explains Dr. Cameron Akbari, co-director of Non-Invasive Vascular Medicine at Boston's Beth Israel Deaconess Medical Center. "That can cause a pulmonary embolus, which can be fatal. The risk of pulmonary embolus can be as high as 10% with SVT." Accordingly, patients with signs and symptoms of SVT should seek medical advice to see whether other treatment is necessary.

Deep Vein Thrombosis

Deep vein thrombosis occurs when a large blood clot forms in the deep veins of the leg. Dr. Akbari points out, "Unfortunately, only 40-50% of patients have obvious signs and symptoms of DVT. When they do occur, the usual symptoms are pain and/or swelling in the calf or thigh area, usually isolated to one leg."

The factors that generally cause DVT can include the same factors that cause SVT, but DVT often presents with no symptoms and it can be life threatening. A deep vein blood clot always poses the risk of breaking free from the lining of the blood vessel in which it forms, and then traveling through the circulatory system as an embolus or embolism. If the embolism lodges in the lungs, the result can be fatal.

When multiple risk factors for DVT are present and if DVT is suspected—either due to the symptoms listed above or in the absence of symptoms—your doctor will almost certainly order an ultrasound to confirm the diagnosis.

If a deep vein blood clot is found (or if not found but is strongly suspected), quick and decisive treatment is necessary. The treatment consists of the following:

  • Anticoagulation—thinning of the blood, and thus, the blood clot with anticoagulation medication (eg Heparin), followed by three or six months of an oral anticoagulation medication (eg Coumadin).
  • Compression treatment—wearing tight fitting elastic stockings or pneumatic stockings (electrically pumping stockings) to help blood flow. These are usually prescribed several days to weeks after beginning anticoagulation treatment.
  • Hospitalization—to monitor the patient's condition (and to be able to administer emergency treatment if necessary) until the anticoagulant medication begins working. Sometimes, patients can be safely treated on an outpatient basis if they are closely monitored by their physicians. In such cases, anticoagulation treatment begins at home, first with self-injections, followed by oral medication.
  • Filter—if blood thinning treatment is not possible or complications arise in spite of anticoagulation medication, a filter may be surgically placed in the main abdominal vein (the vena cava) to prevent an embolus from reaching the lungs.
  • Surgery—in certain extreme situations, surgery may be needed to remove the clot and partially interrupt the vena cava.


Although SVT and DVT tend to affect people age 40 and older, all adults should take certain measures to avoid developing these conditions. These preventive measures include the following:

  • Avoiding sitting in one position for long periods of time.
  • Moving your legs (standing and walking around for five minutes) every hour or two when traveling.
  • Not smoking, especially, if you're a woman who takes birth control pills or estrogen.
  • Not wearing tight stockings or hosiery that restricts blood flow.
  • Staying physically fit.
  • Maintaining your proper weight.
  • If confined to a bed, moving legs as much as possible to prevent blood from pooling in the veins.

If you are at high risk for SVT or DVT, other preventive measures such as long-term anticoagulation medicine may be prescribed by your physician.

There is some evidence that use of the supplement Pycnogenol (alone or combined with natto, made from soy) prior to a long plane flight might reduce the risk of developing DVT, but discuss the risk and benefits of this medication with your doctor before taking.

In addition, anytime you undergo major surgery there is a risk that a DVT will develop during or following surgery. If you are scheduled to undergo major surgery, consult with both your surgeon and anesthetist beforehand to make certain they take proper precautions, including the wearing of compression stockings and/or administering anticoagulation medication during and following surgery.

Finally, if you experience any of the symptoms of SVT or DVT (or if you develop varicose veins), consult with your physician immediately.


American Heart Association

American Venous Forum


BC Healthguide

Canadian Heart and Stroke Association

Transport Canada


Belcaro G, Cesarone MR, Rohdewald P, et al. Prevention of venous thrombosis and thrombophlebitis in long-haul flights with pycnogenol(r). Clin Appl Thromb Hemost. 2004;10:373-7.

Cesarone MR, Belcaro G, Nicolaides AN, et al. Prevention of venous thrombosis in long-haul flights with Flite Tabs: the LONFLIT-FLITE randomized, controlled trial. Angiology. 2003;54:531-9.

Phlebitis and thrombosis. Vein Disorders Center website. Available at: http://www.veincenter.com/phlebitis.html.

Last reviewed February 2008 by ]]> Jill D. Landis, MD]]>

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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