Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel (a vein or an artery) is injured, the body uses platelets (thrombocytes) and fibrin to form a blood clot to prevent blood loss. Even when a blood vessel is not injured, blood clots may form in the body under certain conditions. A clot, or a piece of the clot, that breaks free and begins to travel around the body is known as an embolus. Thrombosis may occur in veins (venous thrombosis) or in arteries. Venous thrombosis leads to congestion of the affected part of the body.
- Swelling in your foot, ankle, or leg, usually on one side
- Cramping pain in your affected leg that usually begins in your calf
- Severe, unexplained pain in your foot and ankle
- An area of skin that feels warmer than the skin on the surrounding areas
- Skin over the affected area turning pale or a reddish or bluish color