Deep vein thrombosis (DVT) is a blood clot and is a common illness that can result in pain and death if not recognized and treated well. Death can occur when the venous clots break off and form pulmonary emboli (PE), which can block the arteries of the lungs. DVT and PE most often complicate the course of sick patients but may also affect healthy persons. DVT can also be a chronic disease. In those instances in which DVT and PE develop, in addition to the death risk, hospitalization is drawn out and healthcare costs are increased. Therefore, the purpose of this study is to see if we can use ultrasound imaging to determine the type of clots in patients to help better manage their care.