Deep vein thrombosis (DVT) and acute pulmonary embolism (PE) are two manifestations of the same disorder, venous thromboembolism (VTE). DVT of the lower extremity is subdivided into two categories (figure 1):
●Distal (calf) vein thrombosis, in which thrombi remain confined to the deep calf veins or the muscular calf veins, and
●Proximal vein thrombosis, in which thrombosis involves the popliteal, femoral, or iliac veins.
This concept is supported by the fact that over 90 percent of cases of acute PE are due to emboli emanating from the proximal veins of the lower extremities [1,2]. In addition, anticoagulation is highly effective therapy for both conditions. As a result, tests designed to diagnosis DVT are also of importance for the diagnosis of acute PE.
The tests that may be used to confirm the presence of suspected lower extremity DVT and an overview of the usefulness of noninvasive testing in diagnosing acute PE in adults will be reviewed here . The evaluation of the patient with venous thrombosis, with emphasis on the indications for and methods of screening for a hypercoagulable state, the prevention of DVT, and issues related to DVT in children are discussed separately. (See "Evaluation of the patient with established venous thrombosis" and "Prevention of venous thromboembolic disease in surgical patients" and "Pathogenesis and clinical manifestations of venous thrombosis and thromboembolism in infants and children" and "Diagnosis and treatment of venous thrombosis and thromboembolism in infants and children".)