Deep vein thrombosis is a blood clot that forms in a vein deep inside the body, most often in the leg. If a piece of that clot breaks loose and travels through the bloodstream, it can become caught in the lung, causing a life-threatening condition called a pulmonary embolism.
DVTs can develop in people with conditions that make them prone to blood clots, such as antiphospholipid syndrome. They can also form in people with no history of blood clots but who do not move for a long period of time, such as those recovering from surgery.
To lower a patient's risk of DVT after surgery, a doctor may prescribe a blood thinner such as aspirin or Coumadin. Increasingly, automatic compression devices, which massage the legs to increase blood circulation, are being used alongside or instead of blood thinners to prevent DVTs.