Phlebitis and Venous Thrombosis

Phlebitis (fle-BY-tis) is a general term that refers to the inflammation of a vein. Phlebitis is usually treatable and not dangerous by itself. However, if the inflammation leads to or is accompanied by the formation of a blood clot *

Healthy vein (top) and vein with phlebitis (bottom).

Healthy vein (top) and vein with phlebitis (bottom).
Illustration by Frank Forney. © 2016 Cengage Learning®.

Terry's Tale

Terry decided to visit her doctor after she experienced slight pain in an area of her lower left leg and then discovered a streak of redness in the area. The area was also swollen. The doctor examined the sore spot and then asked her if the pain was worse early in the morning when she swung her leg over the side of the bed. She said it was. He also asked if she spent much time sitting. She said that as a receptionist at a busy office, she might go hours without getting up from her desk. The doctor considered all of the information and told Terry that she had superficial phlebitis. He explained that if she followed his recommendations, she would be back to normal in a week or two. He also told her that he was glad she came into the office, because superficial phlebitis can sometimes lead to more serious health problems.

What Are Phlebitis and Venous Thrombosis?

The heart beats about 100,000 times per day, driving blood through the arteries of the body and back to the heart through the veins. Sometimes, however, the blood in veins does not flow well. It moves slowly or pools in the veins, like water forming a puddle. The pooling of blood causes the walls of the vein to stretch and become inflamed, and it sometimes causes clotting. Clots are gelled, or thickened, clumps of blood that usually have a beneficial function, such as when they help to seal a wound and stop its bleeding. The inflammation of a vein is called phlebitis, and when the affected vein is close to the body's surface, it is known as superficial phlebitis. Superficial phlebitis is often painful but rarely serious.

Deep vein thrombosis is the formation of a blood clot in a deep vein. It affects the large blood vessels deep in the leg. Deep vein thrombosis is potentially life threatening. An embolus can travel in the bloodstream and enter the heart. It can then block the pulmonary * artery, the large artery that carries blood from the heart into the lungs, causing a pulmonary embolism * . This may cause death if not treated rapidly and effectively.

What Causes Phlebitis and Venous Thrombosis?

Phlebitis and venous thrombosis can occur for many reasons. A sedentary lifestyle is a risk factor. Prolonged inactivity or sitting for many hours on long car or plane rides causes pooling of blood in the legs and may cause a vein to become irritated and inflamed. An injury to the legs, a tumor, and some surgeries can inflame or otherwise damage veins and result in a slowed blood flow. People who are confined to bed, either after an operation or in general, are prone to pooling of blood in the leg veins, and some medical conditions increase the clotting potential of blood. Pregnant women are also at greater than normal risk, as are women who take estrogen (ES-tro-jen), a primary female sex hormone * * . Smoking is another major risk factor, along with having varicose veins.

What Are the Symptoms of Phlebitis and Venous Thrombosis?

Phlebitis usually occurs in the legs. Venous thrombosis typically affects the lower legs, the pelvis, or the thigh. However, both phlebitis and venous thrombosis can occur elsewhere in the body. The symptoms for superficial phlebitis and for deep vein thrombosis overlap somewhat. The symptoms of superficial phlebitis include swelling, a red streak in the affected area, and pain that may become worse when walking or when first getting out of bed. Symptoms of deep vein thrombosis include swelling of the leg or arm, which may happen suddenly; leg pain that may develop suddenly or worsen when one stands up or walks; a warm feeling at the affected site that sometimes extends over larger areas; and an enlargement of superficial veins in the area, which may appear reddish-blue.

In the case of pulmonary embolism, symptoms can include heavy sweating; rapid breathing and rapid heart rate; coughing often accompanied by sharp chest pains; back pain; shortness of breath, and fainting or lightheadedness.

How Are Phlebitis and Venous Thrombosis Diagnosed?

Doctors can often diagnose phlebitis simply by asking the patient a few questions and conducting a physical examination. For venous thrombosis, doctors use tests to detect the presence of clots in the veins. One test, venography, is a way of viewing veins that entails injecting dye into a leg vein and taking an x-ray of the veins, a venogram. Doctors can also use ultrasound * to generate an image of the leg that is vaguely similar to an x-ray image. Other techniques used to diagnose venous thrombosis include magnetic resonance imaging * (MRI) and computed tomography * (CT), which generate cross-sectional images of organs, structures, blood vessels, and clots.

According to the Coalition to Prevent Deep Vein Thrombosis, deep vein thrombosis (DVT) affects nearly 1 million Americans per year, and estimates suggest that 60,000 to 100,000 Americans die of DVT each year.

How Are Phlebitis and Venous Thrombosis Treated?

The danger of phlebitis is that it can lead to venous thrombosis. If clots are absent, doctors treat patients with heat packs and anti-inflammatory drugs, such as ibuprofen *

For people at high risk for developing clots, doctors often recommend preventive measures such as the use of drugs that slow or impede the clotting of blood and special compression stockings that help to keep blood from pooling in the deep veins of the legs.

Can Superficial Phlebitis and Thrombosis Be Prevented?

The best prevention is to stay active. Smoking and obesity * increase the risk of superficial phlebitis and thrombosis, so avoiding tobacco and maintaining a healthy weight are both good preventative measures.

See also Embolism • Vascular Diseases: Overview


Books and Articles

Thompson, Amy E. “Deep Vein Thrombosis.” JAMA: Journal of the American Medical Association. May 26, 2015. (accessed August 24, 2015).

Wolbrink, Alex. “Deep Vein Thrombosis and Travel.” Publication AM-40003/2. FAA Civil Aerospace Medical Institute. Aerospace Medical Education Division. (accessed August 24, 2015).


Centers for Disease Control and Prevention. “Venous Thromboembolism (Blood Clots.)” (accessed November 11, 2015).

MedlinePlus. “Deep Venous Thrombosis.” U.S. National Library of Medicine, National Institutes of Health. (accessed August 11, 2015).

NHS Choices. “Deep Vein Thrombosis.” National Health Services. (accessed November 11, 2015).

Thrombosis Adviser, (accessed November 11, 2015).


American College of Phlebology. 101 Callan Ave., Suite 210, San Leandro, CA 94577. Telephone: 510-346-6800. Website: (accessed November 11, 2015).

Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30329-4027. Toll-free: 800-232-4636. Website: (accessed August 11, 2015).

North American Thrombosis Forum. 368 Boylston St., Brookline, MA 02445. Telephone: 617-730-4120. Website: (accessed August 11, 2015).

* blood clot is a thickening of the blood into a jellylike substance that helps stop bleeding. Clotting of the blood within a blood vessel can lead to blockage of blood flow.

* pulmonary refers to the lungs.

* embolism is a blockage in a blood vessel caused by a blood clot, air bubble, fatty tissue, or other substance that traveled through the bloodstream from another part of the body.

* hormone is a chemical substance that is produced by a gland and sent into the bloodstream carrying messages that have certain effects on other parts of the body.

* menopause (MEN-o-pawz) is the end of menstruation.

* ultrasound, also called a sonogram, is a diagnostic test in which sound waves passing through the body create images on a computer screen.

* magnetic resonance imaging, or MRI, uses magnetic waves, instead of x-rays, to scan the body and produce detailed pictures of the body's structures.

* computed tomography (kom-PYOO-ted toe-MAH-gruh-fee), or CT, is a technique in which a machine takes many x-rays of the body to create a threedimensional picture. Formerly called computed axial tomography (CAT).

* ibuprofen (eye-bew-PRO-fin) is a nonsteroidal anti-inflammatory drug (NISAD) used to reduce fever and relieve pain or inflammation.

* obesity (o-BEE-si-tee) is an excess of body fat. People are considered obese if they weigh more than 30 percent above what is healthy for their height.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)