Venous thromboembolism, or VTE, is a serious medical condition characterized by a blood clot in a vein, also known as deep vein thrombosis. If the clot breaks free from the vein, it can cause a life-threatening pulmonary embolism by blocking blood supply to the lungs. Over 100,000 Americans may die from VTE per year. If recognized quickly, VTE may be effectively treated with anticoagulant therapy; however, it can be difficult to detect when VTE is occurring and when treatment is warranted, thus the clinical laboratory plays an important role in performing diagnostic tests for VTE.