Thrombophlebitis, briefly described on 10/29/2009, refers to the inflammation of a vein due to a blood clot. Depending on the location of the lesion, thrombophlebitis can be categorized into superficial phlebitis and deep vein thrombophlebitis. The pathological changes include intimal hyperplasia of the blood vessel, narrowing of the vascular lumen, and slowed blood flow. The surrounding skin may appear congested and red.