Phlebitis. Coloured angiogram of a patient with phlebitis of an iliac artery. The large artery running down the centre is the aorta, it branches into the two iliac arteries that serve the legs. The right iliac artery is not seen as it is completely blocked due to phlebitis, inflammation of a blood vessel. The walls of the artery become thicker, narrowing the lumen (inside of the artery). Phlebitis is usually accompanied by a blood clot (thrombus). Treatment is with anti- inflammatories and anticoagulants. Surgery may be used to hold open the artery. The purple object (right) is a catheter used to inject a contrast medium into the blood vessels so they can be seen on the X-ray.