A blood clot in a deep leg vein isn’t apt to send someone rushing off to a doctor. That’s because this type of clot—called a deep venous thrombosis, or DVT—is often symptomless. It usually goes away on its own, and as long as it stays put, it’s not likely to be dangerous.
Trouble is, DVT doesn’t always stay put. Sometimes a fragment breaks off and travels through the bloodstream. When that happens, it’s called an embolus. If the embolus gets carried to the heart, it may end up in an artery that delivers blood to the lungs. At that point, it becomes a life-threatening crisis known as “pulmonary embolism.”
How can a doctor identify DVT? A common test is Doppler ultrasound scanning, which uses sound waves to form a picture. Other methods include contrast venography. an X-ray taken after injecting contrast material into the leg veins; impedance plethysmography, which measures blood flow in the legs; platelet scintigraphy, which traces clots through the veins; and magnetic resonance imaging (MRI).
Although sometimes DVT just happens, most cases occur after surgery, especially following procedures that take place near the pelvis or upper leg. However, any condition that immobilizes a person can raise risk, and susceptibility to DVT rises with age and obesity.
In-bed exercises can prevent DVT in surgical patients. Sometimes anticoagulant drugs are given during and after an operation to prevent clots from forming.
Anticoagulant drugs or thrombolytic drugs are administered during an episode of DVT to dissolve the clot.