The ACEP Clinical Policies Committee regularly reviews guidelines published by other organizations and professional societies. Periodically, new guidelines are identified on topics with particular relevance to the clinical practice of emergency medicine, but for which no ACEP policy is available. This article highlights recommendations for the diagnosis of deep venous thrombosis (DVT), published in the 2012 clinical practice guideline of the American College of Chest Physicians.

Emergency physicians face a number of challenges when looking to make the diagnosis of deep venous thrombosis. First, DVT can present subtly, and clinical assessment alone is typically insufficient, requiring laboratory and imaging techniques to make the diagnosis.

Second, the development of a DVT within the patient’s venous system is a dynamic process, and diagnostic testing might miss the diagnosis in patients presenting early in the course of disease with a minimal clot burden. Third, the consequences of missing the diagnosis may be severe, as untreated DVT can lead to pulmonary embolism.

Clinicians now have several adjunctive technologies for assisting with the diagnosis, including D-dimer testing for the presence of fibrin split products, venous ultrasonography (proximal leg with compression, or whole-leg), and venography (typically by CT or MRI). However, this range of diagnostic testing options has resulted in wide practice variations.

In an attempt to standardize the evaluation of patients with suspected DVT, the American College of Chest Physicians published in February 2012 a clinical guideline on the diagnostic evaluation of these patients. While the document includes nearly 200 pages, the first few pages are user-friendly, highlighting specific recommendations to assist doctors in creating a diagnostic strategy. All recommendations are written in PICO format, and evidence is stratified using the GRADE working group process.

The most important concept from this guideline is that, rather than performing the same tests in all patients, the pretest probability of a DVT should determine the diagnostic pathway, much as is the current practice in the workup of pulmonary embolism. In patients with a low or moderate pretest probability of DVT, initial recommended tests include D-dimer or venous ultrasound.

There is a Grade 2C recommendation weakly favoring D-dimer testing over ultrasonography in this patient population, although patient characteristics (such as comorbid conditions causing elevated D-dimer levels) and technical factors (such as local availability and cost) should be taken into account. If either the D-dimer or venous ultrasound is negative, no further testing is warranted (Grade 1B). If the D-dimer is positive, venous ultrasound should be performed to confirm presence of a thrombus. This decision tree is presented as a graphical flow diagram in the guideline, and may represent the most widely applicable algorithm for the majority of patients presenting to the emergency department with suspicion for deep venous thrombosis.