It is basically inflammation of a vein, often accompanied by the formation of a clot. It occurs mainly as a result of injury to a vessel wall, chemical irritation of the vessel, or after a long period with an intravenous catheter. In a superficial vein, phlebitis is easily seen: palpation reveals a hard, cord-like vessel, very sensitive and tender to touch. The region around it may be reddened and hot to touch. Phlebitis of a deep vein is characterized by the presence of pain and cramps, and tends to be common in the calf area.