Deep Vein Thrombosis (DVT)
What is DVT?
Deep Venous Thrombosis is the formation of blood clot in the deep veins, most commonly the legs. The clot may cause the blood to back up in the veins and result in pain and swelling.
What are some of the risk factors for developing DVT?
- Birth Control Pills
- Family history of blood clotting disorders
- Increased weight
- Prolonged inactivity such as extended sitting during a plane or car ride or after a fracture or surgery
- Cigarette smoking
How is DVT diagnosed?
Detecting DVT on a physical exam can be very difficult, and imaging tests are an important part of the work up. Duplex ultrasound imaging is the primary diagnostic tool utilized to diagnose DVT. In the uncommon situations where ultrasound imaging cannot make the diagnosis other tests may be utilized. Some deep veins in the body such as in the pelvis and abdomen can be more difficult to image with ultrasound , and magnetic resonance venography (MRV), which relies on magnetic waves for imaging can be useful. When the diagnosis remains uncertain, or for areas that may be difficult to image with ultrasound or magnetic resonance, a venogram may be necessary. A venogram is performed by placing an intravenous catheter in the extremity and x-ray dye is injected while x-rays are taken. CT scanning (computerized tomography) during x-ray dye injection can also be helpful in certain situations.
What are the risks of DVT and how can they be prevented?
The most feared risk of DVT is pulmonary embolus (PE). A PE occurs when the clot in the leg breaks off and travels to the heart and lungs. PEs can be life threatening , but fortunately a PE doesn’t occur in the majority of DVTs. Prompt diagnosis and therapy are important. DVT is usually treated with blood thinners such as heparin and Coumadin with alternative blood thinners recently introduced in the US. The blood thinners help prevent additional blood clots from forming and also help prevent a PE from occurring. In patients who can’t tolerate blood thinners because of an increased risk of bleeding, a temporary or permanent filter can be placed in the abdomen in the main draining vein of the legs (the inferior vena cava). The filter is placed in the vein through a small puncture in the neck or groin and guided into position by x-ray fluoroscopy. Another risk of DVT is damage to the valves that help prevent blood from refluxing backwards in the veins as it returns to the heart. When the valves are damaged, patients can develop post thrombotic syndrome (PTS), which is characterized by chronic leg swelling and discoloration, varicose veins, and the development of ulcers. Blood thinners can also help prevent PTS, and compression stockings, walking, and weight loss have also been shown to reduce the incidence. Recent data suggests that removal or dissolving the clot may help prevent PTS.
By Robert M. Varnell, M.D. – Vascular and Interventional Radiologist, Triad Radiology Associates