Deep vein thrombosis (DVT) is a blood clot that forms in a vein deep in the body. Blood clots happen when blood thickens and clumps together.
Clots can cause symptoms like swelling, discomfort, cramps, and redness or discoloration on the leg. But many cases—up to 50 percent— may go unnoticed. In fact, some people may not realize they have a clot or symptoms of a clot until it develops into something more serious.
Blood clots most often happen in the veins, instead of the arteries, because blood travels slower than in the arteries. However, blood clots in the arteries can also happen.
Most deep vein blood clots happen in the lower leg or thigh. This is because blood pressure in our veins is lower in the areas of the body that are farther away from the heart. So, our leg veins are more susceptible to situations where blood flow can be interrupted.
Some blood clots can break off and travel through the bloodstream. This loose clot is called an embolus.
An embolus can be very dangerous. Sometimes they travel to an artery in the lungs and block blood flow. That creates what’s called a pulmonary embolism (PE). A PE can damage the lungs and other organs in the body and cause death.
While DVT and PE can affect anyone, your risk of a blood clot is higher if you’ve been traveling for long periods of time, have been ill and in bed for a while, or have had surgery. Chronic heart conditions, cancer, stroke, and paralysis (not being able to move) can also increase your chances of getting a clot.