Thrombophlebitis (throm-boe-fluh-BY-tis) occurs when a blood clot blocks one or more of your veins, typically in your legs. Rarely, thrombophlebitis (sometimes called phlebitis) can affect veins in your arms or neck.
The affected vein may be near the surface of your skin, causing superficial thrombophlebitis, or deep within a muscle, causing deep vein thrombosis (DVT). Thrombophlebitis can be caused by trauma, surgery or prolonged inactivity. Superficial thrombophlebitis may occur in people with varicose veins.
A clot in a deep vein increases your risk of serious health problems, including the possibility of a dislodged clot (embolus) traveling to your lungs and blocking an artery there (pulmonary embolism). Deep vein thrombosis is usually treated with blood-thinning medications. Superficial thrombophlebitis is sometimes treated with blood-thinning medications, too.