A condition in which a blood clot blocks one or more veins.

Venous thrombosis, or thrombophlebitis, happens when a blood clot blocks one or more veins. It typically happens in the legs and can be life-threatening if the clot gets loose and travels to the lungs. The condition can be caused by major injury, surgery or being immobile for too long, such as when hospitalized.

Symptoms depend on the location of the clot. They may include pain that feels like a muscle cramp and leg swelling. If the clot travels to the lungs, symptoms may include shortness of breath and chest pain.

Treatment usually involves medicines to stop the blood from clotting. If it's severe, surgery may be needed.