Arteries seem to get more of the limelight than veins, mostly because their blockage can rapidly damage bodily organs, and even bring about death. When veins get blocked, a different set of problems can ensue. A deep vein thrombosis (DVT) is a blood clot which forms in one of the large veins, far below the skins surface. Usually the legs are affected, resulting in swelling, but sometimes the arms can be involved. The risk factors for the development of a clot are neatly summarized in Virchows Triad. The first of three factors is stasis or slow blood flow, like when you sit for prolonged periods of time on a plane flight. The second is endothelial injury, or vessel wall injury, which can be caused by hypertension or high cholesterol. The last is a hypercoagulable state (blood more likely to form clots), which can be induced by genetic factors, severe kidney disease, malignancy, trauma, and burns.