Superficial vein thrombosisSuperficial vein thrombosis (SVT) is a blood clot formed in a superficial vein, a vein near the surface of the body. Usually there is thrombophlebitis, which is an inflammatory reaction around a thrombosed vein, presenting as a painful induration (thickening of the skin) with redness. SVT itself has limited significance (in terms of direct morbidity and mortality) when compared to a deep vein thrombosis (DVT), which occurs deeper in the body at the deep venous system level.