Ultrasound evaluation for deep venous thrombosis (DVT) is one of the 11 core ultrasound applications for emergency physicians as listed in the 2008 and revised 2016 American College of Emergency Physicians guidelines.1 This evaluation typically consists of a limited compression ultrasound (CUS) of the proximal lower extremities. Although different from a typical “duplex” examination performed in many vascular laboratories in the United States, which consists of a combination of whole-leg CUS and Doppler ultrasound, limited CUS has been widely studied as the initial investigative tool for the diagnosis of DVT.2,3
If left untreated, DVT can lead to significant morbidity and mortality, including pulmonary embolism (PE) and postthrombotic syndrome. The annual incidence of venous thromboembolism is approximately 1 in 1000 and increases with age. Since two thirds of patients with venous thromboembolism are initially diagnosed with proximal lower extremity DVT, this leads to an annual incidence in the United States of approximately 200,000 DVTs.4 Without treatment, 50% of these will progress to PE with a resultant 30 days mortality of approximately 15%.4 With treatment, the complications of DVT are reduced to less than 5%. However, anticoagulation causes major bleeding in almost 2% of patients and mortality in 0.2%, so treatment should be limited to only those diagnosed with the disease.5 Therefore, diagnostic strategies need to have a high sensitivity and specificity.
The vast majority of DVTs (>90%) are diagnosed in the proximal veins of the lower extremity (common femoral vein, femoral vein, and popliteal vein). The iliac veins account for about 2% of DVTs.6 Upper extremity veins account for a small share of DVTs, unless a venous catheter is present.
The approach to isolated calf vein DVTs is still a source of great controversy. The debate over the best diagnostic approach centers around the tendency of these to propogate proximally. Strategies include: (1) repeat ultrasound in 1 week, (2) D-dimer testing for patients with a negative limited CUS, and (3) a single whole-leg ultrasound.3 Superficial thrombophlebitis had been thought to never progress to DVT, though some studies are challenging that and even suggest treating for superficial thrombophlebitis involving the proximal greater saphenous vein.7
Clinical signs and symptoms of DVT consist of leg swelling and tenderness; however, only about 20% of patients who are clinically suspected of having a DVT actually have one. High-sensitivity D-dimer assays, when negative, have been shown to help rule out DVT in patients with a low clinical suspicion.8 Ultrasound of the proximal lower extremities has become the gold standard imaging test for diagnosing DVT. Most current algorithms for assessing patients with suspected lower extremity DVT involve using a combination of clinical suspicion, high-sensitivity D-dimer assays, and CUS of the lower extremity.8,9
Emergency medicine providers are uniquely qualified to use a combination of ...