Phlebitis is a condition where the veins close to the surface of the body (superficial veins) are inflamed thus becoming swollen and reddened. The inflammation causes a blood clot to form in the vein, and usually occurs in leg veins, but it may occur in an arm following improper injections. The thrombus in the vein causes pain and irritation; it may hinder blood flow in the veins. Phlebitis occurs in the surface (superficial) and thrombosis in the deep veins.
Superficial phlebitis affects veins on the skin surface. The condition is rarely serious and, with proper care, usually resolves rapidly. Sometimes people with superficial phlebitis also get deep vein thrombophlebitis, so a medical evaluation is necessary.
Deep vein thrombosis affects the larger blood vessels deep in the legs. Large blood clots can form, which may break off and travel to the lungs. This is a serious condition called pulmonary embolism. This situation is rare in superficial thrombophlebitis
Phlebitis occurs in people with poor blood circulation or in veins damaged from intravenous drug use or an intravenous catheter. It can be a complication due to a medical or surgical procedure. Since Phlebitis is often caused by an injury to a vein, one is more likely to get phlebitis in veins where the blood flows more slowly than normal, such as varicose veins. A clot, called a thrombus, can form and adhere to the vein wall. Since there are no muscles to push the clot, it stays stuck inside the vein and blocks blood flow.
Phlebitis can also be a complication resulting from connective tissue disorders such as lupus erythematosous, or of pancreatic, breast, or ovarian cancers.
Some risk factors for phlebitis include the following: