Phlebitis is defined as the inflammation of a vein. Thrombophlebitis is a phlebitis associated with a blood clot. Phlebitis can affect veins near the surface of the skin (superficial phlebitis) or veins deeper within a muscle (DVP, Deep Vein Phlebitis). Any vein can be affected by a phlebitis but the legs are most often involved. Phlebitis is usually caused by an injury to the vein (surgery, catheter insertion) or any condition that reduces the blood flow in a vein: venous insufficiency, prolonged immobilisation (prolonged illness, long plane trip, etc.). Pregnancy, certain drugs and hereditary disorders of coagulation can also cause phlebitis. Some severe deep phlebitis will paradoxically not be accompanied by significant symptoms while warmth, pain, sensitivity, redness and swelling will be the hallmark of many benign superficial ones. In deep vein thrombophlebitis, there is risk that the blood clot (thrombus) becomes dislodged, can travel to the lungs and block an artery causing a pulmonary embolism. Rapid heart rate, marked shortness of breath are the most significant symptoms of pulmonary embolism, a medical emergency. The diagnosis of phlebitis is based on clinical observations completed for deep vein phlebitis by Doppler sonography and in some cases by measuring the blood level of clot fragments called D-dimers.