Use of US in the evaluation of patients with symptoms of deep venous thrombosis of the lower extremities.

Deep venous thrombosis (DVT) is a major health problem and is estimated to have an incidence of 600,000 cases per year. Clinical signs and symptoms of DVT are unreliable. If clinical signs alone were used to diagnose DVT, 42% of patients would receive unnecessary anticoagulation therapy. Most patients evaluated with ultrasonography (US) do not have DVT. The key to making a precise diagnosis is recognizing the characteristics of various diseases on US images. The anatomic approach is the most useful strategy for characterizing the spectrum of pathologic conditions seen in patients with symptoms that simulate DVT. The inferior extremity can be divided into four regions-inguinal, thigh, popliteal, and lower leg-with the rough limits defined for each as they are examined at US. The differential diagnoses affecting the lower extremities include infectious, neoplastic, traumatic, inflammatory, vascular, and miscellaneous entities. Some pathologic conditions seen in the inguinal region are adenopathies, lymphangitis, soft-tissue tumors, hematomas, adductor tendonitis, and hernias. In the thigh, cellulitis, myositis, abscess, benign and malignant tumors, and sports-related lesions are seen. In the popliteal region, cellulitis, arthritis, benign and malignant masses, muscle contusions, ruptured popliteal cysts, and thrombophlebitis are seen. And in the lower leg, cellulitis, lipomas, tennis leg, superficial thrombophlebitis, tendonitis, and soft-tissue hydrostatic edema secondary to cardiac and renal failure can simulate DVT.