What Is Deep Vein Thrombosis (DVT)?
Deep vein thrombosis (DVT) occurs when a blood clot develops in a vein deep in the body. Deep veins are found within groups of muscles. The veins close to the skin are called superficial veins.
DVT commonly affects the leg veins, such as the femoral vein, the popliteal vein, or the deep veins of the pelvis, but may also appear in the upper body, such as the arms or other locations in the body.
In the United States alone, 600,000 new cases are diagnosed each year. It is estimated that there are more than 2.5 million persons in the U.S. who develop deep vein thrombosis each year. Deep vein thrombosis is a risk for any major surgery, but patients who have surgery of the legs or hips are at higher risk.
Deep vein thrombosis can pose a serious threat to health. Pieces of a clot can break off and travel through the bloodstream to the lung. This is called a pulmonary embolism and can be fatal soon after it occurs. Deep vein thrombosis can also block blood flow in the veins, causing the blood to pool. This can cause swelling, pain, and permanent damage to the leg called post-thrombolic syndrome.
What is thrombophlebitis?
When a clot forms in a vein, inflammation of the vein may occur at the affected site. This is referred to as thrombophlebitis. Inflammation may be minimal, or may be more pronounced, causing swelling, redness, warmth, and tenderness at the site. When thrombophlebitis occurs, the body’s response to inflammation may promote the formation of more clots.
Symptoms of Deep Vein Thrombosis (DVT)
Deep vein thrombosis occurs without symptoms about 50 percent of the time. When symptoms do occur, they may include:
- Swelling in one or both legs
- Pain
- Warm skin
- Discoloration (bluish or reddish) of the skin
The symptoms of deep vein thrombosis may resemble other medical conditions or problems. Always consult your physician for a diagnosis.
Causes of Deep Vein Thrombosis (DVT)
There are a variety of risk factors that contribute to the development of deep vein thrombosis:
- Surgery, particularly surgery of the hip or leg, or abdominal surgery
- Trauma or bone fracture
- A long period of bed rest or sitting for a long time (e.g., on an airplane or in a car)
- Cancer
- Pregnancy
- Birth control pills or hormones taken for symptoms of menopause
- Varicose veins
Risk factors for deep vein thrombosis
A risk factor is anything that may increase a person’s chance of developing a disease. It may be an activity, diet, family history, or many other things.
Although these risk factors increase a person’s risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop the disease, while others develop disease and have no known risk factors. Knowing your risk factors to any disease can help to guide you into the appropriate actions, including changing behaviors and being clinically monitored for the disease.
Risk factors related to or that may contribute to deep vein thrombosis and thrombophlebitis include, but are not limited to, the following:
- Obesity
- An inherited tendency that increases risk for blood clots
- Age (greater than 60)
- Type A blood group
Who is at risk to develop chronic DVT?
- Cancer patients
- Patients taking hormonal contraceptives (birth control pills)
- Patients who are pregnant
- Patients who have undergone recent surgery
- Patients who are immobilized
- Patiens with a family history of blood clots
Acute DVT
Treatment of acute DVT
The goal in the treatment of acute DVT is to restore blood flow. Once the clot is removed or dissolved, swelling and pain typically resolve.
At Stanford we have a variety of techniques, drugs and devices that can be used to remove the blood clot. The procedure involves placing a catheter, similar to an IV into the blocked vein. Depending on how much clot is present and how old the clot is determines which device we use.
Standard anticoagulation with coumadin, heparin or low molecular weight heparin (i.e. lovenox) prevent more clot from forming, but does not remove the existing clot from the vein. This therapy relies on the body to “dissolve” the clot. Unfortunately, this often does not occur and the vein will remain blocked forever.
At Stanford we have a variety of new devices and methods that remove the clot from the vein. Some devices allow us to administer a “clot-busting” drug directly into the clot. Other devices break up the clot into tiny pieces that are then removed using a suction catheter. Often, these techniques uncover a particular narrowing of the vein that caused the blood clot to form, and we are able to treat this by implanting a stent to open the vein. This can require a brief or over-night hospital stay.
Patient outcomes
Patients with the best outcomes are those that have had symptoms for only a short period of time, less than 14 days. The clot responds very favorably when it is “fresh”.
Unfortunately, many physicians that are not interventional radiologists are unaware or unfamiliar with these new techniques and may not act upon new clots. We recommend a consultation with our experienced Stanford faculty.
Chronic DVT
A clot that is over one to two months old is called “chronic.” The clot becomes harder and scars the vein. As a result of this process, the vein becomes much smaller and does not allow blood to flow through effectively.
Symptoms of chronic DVT
Patients with chronic DVT experience leg swelling, pain, and often skin discoloration of the leg below the knee. These patients are typically prescribed compression stockings in order to help with these symptoms. These symptoms are related to the vein being blocked and not allowing blood flow out of the leg.
Treating chronic DVT
At Stanford we have a variety of new techniques to re-open veins that have been blocked for years. We have opened up veins that have been blocked for 25 years, with significant improvement in the patients’ symptoms.
We usually place metal stents into these blocked veins to keep the veins open. The stents are similar to those put in the heart, except the stents we use in veins are much larger. Placing the stents usually does not require more than a band-aid where we entered the vein. This typically requires a short hospital stay.
Of particular interest to our faculty are blood clots that occurred while on oral contraceptives, also known as birth control pills or while pregnant. We have developed an effective method to treat these women, and get them back to their active lifestyle.
Diagnosing Deep Vein Thrombosis (DVT)
In addition to a complete medical history and physical examination, diagnostic procedures for deep vein thrombosis may include the following:
Treatment for Deep Vein Thrombosis (DVT)
Specific treatment will be determined by your physician based on:
- Your age, overall health and medical history
- Extent of the disease
- Your signs and symptoms
- Your tolerance for specific medications, procedures, or therapies
- Expectations for the course of the disease
- Your opinion or preference
The goal of treatment is to prevent the clot from growing, to ensure that it does not break off and travel through the veins to the lungs, and to help reduce the possibility of another blood clot forming.
Treatment may include: