A blood clot is called a thrombus. The process of clotting inside a blood vessel is called thrombosis. When clotting occurs in the veins, it is called venous thrombosis or thrombophlebitis. Deep vein thrombosis is a serious condition, sometimes leading to a pulmonary embolism. A pulmonary embolism is a dislodged fragment of the blood clot that floats through the vein and becomes lodged in the lungs.
Pulmonary embolism is a very serious condition and one of the leading causes of sudden death.
Superficial vein thrombosis is not as serious and rarely needs treatment. The cause of venous thrombosis is unknown. It is associated with a number of conditions or risk factors. Your health care provider will examine you and ask about your symptoms and medical history. Most clots are located in the legs, but they can occur in any vein of the body.