EVIDENCE BASED CLINICAL INSIGHTS FOR HIGH PERFORMING EMERGENCY PHYSICIANS
Wednesday, December 7, 2011
2-Point Compression Ultrasound for DVT in the ED
The incidence of venous thromboembolism (VTE) in the US approaches 600,000 patients with up to 100,000 deaths related to pulmonary embolus (PE).1,2 Fully 90% of PEs originate from deep venous thrombi (DVT) in the proximal vessels of the lower extremities, necessitating diagnostic skill in the emergency physician (EP) to clinch this diagnosis.
Unfortunately, signs and symptoms associated with DVT (palpable cord, ipsilateral edema, warmth, venous dilation) are insufficient to diagnose this condition.5 Ultrasound has replaced venography as the diagnostic study of choice in DVT, but the limited availability of this study outside banker’s hours places the EP in a precarious position -- the presence of untreated DVTs and inappropriate anticoagulation pose separate and meaningful harm to the patient.
Recent data suggest that bedside ultrasonography performed by EPs may be adequate for diagnosis of DVT. After a 30-hour training course for EPs in whole-leg ultrasound, sensitivity approaches 95%.6 However, a whole-leg study takes 13 minutes and the cost/benefit of this training course is unfeasible to many practitioners.
An alternative is the ‘2-point compression’ exam that takes 3 minutes and requires far less training for EPs. Crisp et al. found physicians with varying levels of ultrasound experience were able to diagnose proximal DVTs with 100% sensitivity and 99% specificity (using radiology performed proximal DVT scans as the gold standard) after a 10-minute training program detailing the 2-point compression technique.7
This technique utilizes compression analysis of two sites with a 5-10 MHz linear-array probe:
1. Popliteal vein -- visualized with patient prone, probe in the mid-popliteal fossa.
2. Common femoral vein -- visualized with patient supine, probe at the inguinal ligament.
The exam is considered positive if the vessel is not compressible or a thrombus is visualized.8
The 2-point technique has been compared with whole-leg ultrasound for DVT, and rates of identifying proximal DVT were similar in randomized prospective studies. The 2-point technique did miss isolated calf DVTs when compared with the whole-leg exam. Yet, long-term clinical outcomes were equivalent between the two groups, questioning the clinical significance of anticoagulating calf DVTs.9
In conclusion, EPs are clearly capable of obtaining accurate results in the diagnosis of proximal DVT with bedside 2-point compression ultrasound after appropriate training.
-- Peter Acker MD MPH
1) Cushman M, Tsai AW, White RH, et al. "Deep vein thrombosis and pulmonary embolism in two cohorts: the longitudinal investigation of thromboembolism etiology." Am J Med 2004; 117:19.
2) Beckman MG, Hooper WC, et al. " Venous Thromboembolism: A public Health Concern." Am J Prev Med. 2010 Apr; 38 (4Suppl): S495-501.
3) Havig O. "Deep vein thrombosis and pulmonary embolism. An autopsy study with multiple regression analysis of possible risk factors." Acta Chir Scand Suppl 1977; 478:1.
4) Galanaud JP, Sevestre-Pietri MA, Bosson JL, et al. "Comparative study on risk factors and early outcome of symptomatic distal versus proximal deep vein thrombosis: results from the OPTIMEV study." Thromb Haemost. 2009; 102:493.
5) Sandler DA, Duncan JS, Ward P, et al. "Diagnosis of deep-vein thrombosis: comparison of clinical evaluation, ultrasound, plethysmography, and venoscan with x-ray venogram." Lancet . 1984;2:716–18.
6) Magazzini S, Vanni S, Toccafondi S, et al. "Duplex ultrasound in the emergency department for the diagnostic management of clinically suspected deep venous thrombosis." Acad Emerg Med. 2007;14:216-220.
7) Crisp JG, Lovato LM, Jan TB. " Compression Ultrasonography of the Lower Extremity With Portable Vascular Ultrasonography Can Accurately Detect Deep Venous Thrombosis in the Emergency Department." Ann of Emerg Med. 2010; 56, 6: 601-610.
8) Cogo A, Lensing AWA, Koopman MMW, et al. "Compression ultrasonography for diagnostic management of patients with clinically suspected deep vein thrombosis: prospective cohort study." BMJ. 1998; 316(7124):17-20.
9)Bernardi E, Camporese G, Büller HR, et al. "Serial 2-point ultrasonography plus D-dimer vs whole-leg color-coded Doppler ultrasonography for diagnosing suspected symptomatic deep venous thrombosis: a randomized controlled trial." JAMA. 2008; 300:1653-1659.