Venous Thromboembolic Disease (VTE)

Venous Thromboembolic Disease (VTE)

There are two types of blood clots that occur in veins: deep venous thrombosis (DVT), which occurs in the large main (deep) veins of the body, and superficial thrombosis or thrombophlebitis, which occurs in the veins at the skin surface, almost always of an arm or leg. Venous blood clots block the flow of blood in the vein and cause inflammation, pain, and swelling. Most venous blood clots occur in the legs, with less than 15 percent developing in the veins of the arms or elsewhere (neck or belly).

Superficial Vein Thrombophlebitis

Superficial thrombophlebitis is a clot of the veins in the skin or the layer of fatty tissue just under the skin. This type of clot can occur out of the blue (like in a cluster of large varicose veins) or after an injury (including a blood draw or IV). In general, superficial thrombophlebitis is not dangerous, but it can be painful until it resolves. A superficial thrombophlebitis will feel like a hard, tender lump in the vein or like a small rope underneath the skin’s surface. Often the skin over the top of the vein is red. Superficial thrombophlebitis can take several weeks to go away.

Complications are rare but include:

  • Hyperpigmentation, or darkened skin, where the clot occurred
  • Infection of the clot – fever, chills, spreading or streaking redness over the involved vein, pus draining from a wound over the vein (i.e., old IV location)
  • Spread of the clot into the deep veins

Typically, treatment is anti-inflammatory medication (like ibuprofen), compression stockings, and heat (heating pad or warm compress). Treatment of varicose veins, if present, should be considered to prevent future episodes of superficial thrombophlebitis.

Deep Venous Thrombosis (DVT)

Deep venous thrombosis is a blood clot that occurs in the deep vein system, most often in the leg or low abdomen (pelvis) but also occasionally in the arm. The main symptoms of DVT are sudden pain and swelling of the limb. Diagnosis of DVT can be as simple as an ultrasound. The three classic factors contributing to the development of DVT are tissue injury (like an accident or an operation), immobility (not moving for long periods of time) and a tendency to develop blood clots (whether due to an inherited gene, or other medical conditions or medications).

Common DVT Risk Factors

  • Inactivity (i.e., during long plane or car rides, periods of bedrest from surgery, paralysis, or if a person has leg casts or braces)
  • Active smoking
  • Use of birth control pills or hormone replacement therapy
  • Extreme dehydration
  • Obesity
  • Pregnancy
  • Family history of blood clots
  • Cancer and cancer treatment

A very small percentage of people with DVT have an occult (not yet detected) cancer. For this reason, we remind patients with DVT and the appropriate risk factors for cancer to consider any overdue routine cancer screening exams (mammography, colonoscopy, prostate evaluation).

DVT can cause permanent damage to the valves in the leg veins and venous insufficiency. Symptoms of venous insufficiency include permanent leg swelling, darkened color and thickening of the skin of the lower leg, varicose veins, and feelings of aching, throbbing, tightness, or fullness in the leg. The leg can have areas of dry, reddened, cracked, and itchy skin. One-half of patients with DVT will develop scarring in the involved deep veins with long-term skin damage and leg swelling (also known as a post-phlebitic or post-thrombotic syndrome), which can lead to skin infection and wounds. Repeat DVT occurs in up to one-third of patients within ten years.

The biggest concern with DVT is that the blood clot can break apart and travel through the veins to the heart and lungs, causing a pulmonary embolus (PE), which is fatal in 10-30% of cases. Sudden chest pain, shortness of breath, and/or coughing up blood may be symptoms of a pulmonary embolus. An estimated 40-50% of patients with DVT involving the thigh or pelvic veins will have PE at the same time.


The standard treatment for all DVT or PE is blood-thinning medicine (anticoagulation) for 3-6 months, or longer depending on the reason for having the clot. Blood thinning medicines do not dissolve clot but instead stabilize clot and prevent new clot from growing, which gives the body time to dissolve the clot already there via its own natural process. Warfarin (coumadin) has been the most widely used anticoagulation pill worldwide but has drawbacks in that it takes several days or more to reach full effect in the blood, which means that patients must receive a second blood-thinning medicine at the same time until blood tests show that the blood is thin enough.

Furthermore, repeat blood tests are required at least once or twice a month while taking warfarin to check how thin the blood is and make sure it is not too thinned. The effect of warfarin can vary depending on what food you eat and other medications you take. The benefits of warfarin are that it is easily reversible in an emergency, and it is also easy to get at a very low cost. There are newer “direct” blood-thinning pills that start working as soon as you take them, do not need any blood monitoring, and do not have food or medication interactions. However, these can be expensive and also do not have a commonly available way of reversing its effect. Lastly, there are anticoagulants that can be given by vein or by injection into the fatty tissue of the skin; these normally are used for only a few days (like in combination with warfarin) or while a patient is in the hospital and not able to eat. Anticoagulation may be considered high risk for patients with bleeding problems, recent surgery, or recent severe injury (like a major car accident), and if so, there should be a discussion about other treatment options (see IVC filter below).

DVT Thrombolysis and Thrombectomy

Some people with DVT may be candidates for venous thrombolysis and/or thrombectomy, which is a minimally invasive procedure to directly dissolve or remove a clot. The patients for whom this is indicated have deep vein clots extending from the thigh to the abdomen and almost always have severe leg swelling and pain. The goal of this procedure is to actively reduce the amount of blood clots and reopen the vein, which allows leg swelling and pain to improve more quickly. It also may reduce the chances of long-term complications related to venous hypertension. Afterward, the patient must still continue on blood thinners for several months, as described above, to prevent clots from occurring again. Thrombolysis and thrombectomy are done using a wire and catheter that is placed into the vein, usually from the back of the knee. Thrombolysis is a procedure that releases clot-dissolving medicine directly into the clot in the vein; this usually takes 24-48 hours for complete effect and requires monitoring in the intensive care unit. Thrombectomy involves the use of a specialized catheter to suction clot out from the blood vessel and usually takes 2-3 hours. Thrombectomy and thrombolysis are sometimes done in combination in order to remove as much of the clots as possible.

The main risk of thrombolysis is causing bleeding, therefore thrombolysis is not recommended for elderly or frail patients, or those with bleeding problems, recent surgery, or recent severe injury. It generally does not work on clots that have been in place for more than a few weeks, but thrombectomy can sometimes be effective in those cases.

Inferior Vena Cava (IVC) Filter

The standard of care for the treatment of DVT is anticoagulation, but if you cannot take blood thinners for the reasons mentioned above, or if you have a new or worsening clot despite being on a blood thinner, your physician may advise the placement of an IVC filter.

The right and left iliac veins carry blood from the legs back up to the heart. These veins join together at about the belly button level to form the vena cava, which then leads back to the heart. An inferior vena cava filter, or IVC filter, looks like an umbrella without any fabric and acts to trap blood clot that might try to travel from the legs to the heart (pulmonary embolus, or PE). There is a hook at the top of all modern filters that allow the filter to be removed when reasonable.

Placement of an IVC filter is a minimally invasive procedure performed through a small needle hole in the vein either at the base of your neck or at the groin. A wire and catheter are directed into the vena cava. The filter is inserted through the catheter and left in the vena cava below the kidneys. This procedure takes 30-60 minutes. You can’t feel the IVC filter in your belly, and it will not set off airport scanners. Almost all IVC filters are safe for MRI.

In most cases, it is recommended to remove the filter as soon as the patient does not need it anymore. Removing an IVC filter involves a second catheter procedure through the vein at the base of the neck. A tiny lasso called a snare is used to grab the hook at the top of the filter, which enables the filter to be taken out from the body. This can be done as an outpatient procedure under a light sedative; most filters can be removed in as little as 30 minutes but some can take longer. When a filter has been in place for more than a few months, the procedure can be difficult, and the chances of removing it decrease, in which case it can be left where it is. In certain situations when a patient’s risk of developing more blood clots is expected to always be high, a filter can be placed permanently as protection against pulmonary embolus.