72 - Lower Extremity Venous Ultrasonography

statistically and found to be of little value in reliably determining the presence or absence of DVT. The differential diagnosis for leg pain and swelling includes lymphedema, chronic venous insufficiency, infection (cellulitis), aneurysm, pseudoaneurysm, Baker cyst, and other musculoskeletal causes. Diagnosis of DVT depends on the clinician’s pretest probability assessment and a combination of several noninvasive diagnostic tools (lower extremity ultrasound, D-dimer, or both). The exact diagnostic path or algorithm pursued depends somewhat on local availability and expertise. When available, lower extremity ultrasound is the primary modality used to diagnose or exclude DVT. The lower extremity ultrasound may be a proximal lower extremity examination, a whole-leg examination, or an abbreviated, two-point compression examination. If proximal lower extremity ultrasound is performed, current practice guidelines recommend that ultrasound of the proximal veins be repeated 5 to 7 days after an initial negative result to safely exclude clinically suspected DVT. This recommendation stems from the observation that up to 20% of cases of distal DVT may propagate into the proximal veins. A systematic review and metaanalysis published in 2010 found that after a negative whole-leg study, anticoagulation may be withheld safely without the need for a repeated ultrasound examination. Despite the numerous benefits of lower extremity sonography, many emergency providers continue to be unable to obtain lower extremity ultrasound after hours, on weekends, and on holidays. Clinician-performed two-point compression lower extremity ultrasound is now considered an appropriate method for assessing lower extremity DVT in the emergency department (ED) and is one of the 11 core emergency ultrasound applications. Emergency providers who perform two-point compression lower extremity sonography have demonstrated scan times of less than 4 minutes per patient and time savings of more than 2 hours in terms of time to patient disposition. When ultrasound is not available, providers may be forced to administer low-molecular-weight heparin and either keep the patient in the ED overnight or coordinate an outpatient study for the patient the following day. Although the risk for bleeding in these situations is low, boarding the patient in the ED or relying on patient-initiated follow-up is less than ideal. Given ever-increasing patient volumes and ED crowding, the value of clinician-performed two-point compression lower extremity ultrasound cannot be overstated. • Lower extremity ultrasound is the primary modality used to diagnose or exclude deep vein thrombosis (DVT). • Clinician-performed bedside ultrasound can be accurate in detecting DVT when compared with radiology-performed examination. • Two-point compression lower extremity ultrasound is a simplified approach that consists of compression of the common femoral vessels in the groin and the popliteal vessels in the popliteal fossa. • Compressibility of veins via gray-scale B-mode ultrasound is the most important criterion for assessing DVT. • Current practice guidelines recommend that proximal lower extremity ultrasound be repeated in 5 to 7 days after an initial negative two-point compression result to rule out propagation of unseen distal DVT. KEY POINTS