Deep vein thrombosis (DVT) is a blood clot that forms in a deep vein, often in your leg. Symptoms include swelling, pain, redness and warmth in your leg. Deep Vein Thrombosis (DVT) is the most common type of venous thromboembolism (VTE). It occurs when a blood clot forms in a deep vein, usually in the lower leg, thigh, or pelvis. Learn about DVT symptoms, how to prevent it if you are at risk, and what treatment you may need. The most common life-threatening concern with DVT is the potential for a clot to embolize (detach from the veins), travel as an embolus through the right side of the heart, and become lodged in a pulmonary artery that supplies blood to the lungs. This is called a pulmonary embolism (PE). DVT is a blood clot that forms inside one of the deep veins of the body, most often in the calf or thigh. It can block normal blood return and, more dangerously, break loose and travel to the lungs as a pulmonary embolism. A deep vein thrombosis (DVT) is a blood clot that forms in a vein deep inside your body. WebMD explains what causes it, as well as the symptoms and how you can prevent it. The Wells’ Criteria for DVT Objectifies risk of deep vein thrombosis (DVT) based on clinical findings. Find out more about DVT (deep vein thrombosis), a blood clot in a vein, usually in the leg. Deep vein thrombosis (DVT), which is a blood clot that develops in a deep vein, can cause pain, warmth, swelling, or redness (often in your calf muscle) that doesn’t go away. A DVT can be hard to. Deep vein thrombosis (DVT) occurs when a blood clot (thrombus) forms in one or more of the deep veins in the body, usually in the legs. Deep vein thrombosis can cause leg pain or swelling. There are many different types of blood-thinning drugs used to treat DVT. Together, you and your health care provider will discuss their benefits and risks to determine the best one for you.