An inflamed vein. Phlebitis is an inflamed vein. The problem is that the inflammation is often caused by a thrombus (clot) and the only way to know that a clot is present or not is to have an ultrasound. Clots are common in phlebitis and 24% of the time that a person has phlebitis associated with a clot, they also have a deep venous thrombosis. About 10% of these are associated with a pulmonary embolism.
Inflamed vessel. Plebitis is short for thrombophlebitis which is a blood clot, usually in a vein of the lower leg. It starts with pain in the calf. It may include swelling of the foot and leg. It is best diagnosed by a duplex scan which is an ultrasound picture of the veins of the leg. If there is clot, it may be treated with anticoagulants to prevent extension and avoid it going to the lung (pulmonary embolus).