Phlebitis, inflammation of the coats of a vein. When the internal coat is affected, the blood in the vessel forms a clot or thrombus, and thrombosis and phlebitis are thus associated one with another. The symptoms of phlebitis are the presence of tenderness and reddening over the course of the vessel affected, and this is moreover marked out by the existence of what feels like a hard cord in the position of the vein. Phlebitis may be due to injury, to the extension of inflammation from the tissues surrounding the vein, to gout, and other causes. In suppurative phlebitis the cause of the mischief is a micro-organism. It occurs in connection with wounds which assume a septic condition, in acute necrosis, and in pyaemia.