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Duplex Ultrasound for Thromboembolism

Patients undergoing orthopaedic surgery are at the highest risk for thromboembolic complications. Ultrasound is an important part of the clinician’s armamentarium when evaluating the venous system because of its ease of use, accuracy, portability, and affordability. Normal venous hemodynamic characteristics include spontaneous flow, phasicity, augmentation, valvular competence, and nonpulsatility. In addition, normal venous imaging must demonstrate complete compressibility. Comparison of compression ultrasound and venography in patients with acute deep venous thrombosis (DVT) has consistently demonstrated excellent agreement. Sensitivity ranges from 89% to 100% while specificity ranges from 86% to 100%. Guidelines for symptomatic and asymptomatic DVT evaluation and follow up are discussed. Treatment of acute deep calf vein thrombosis remains controversial; however, the American College of Chest Physicians consensus statement recommends that isolated calf DVT be treated with anticoagulation for 6 to 12 weeks unless there is a contraindication to anticoagulation. Serial follow-ups are to be performed over the next 10 to 14 days to assess for proximal extension of the thrombus if anticoagulation cannot be administered.