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Title: Study Reveals Pros and Cons of 2-Point and Whole-Leg Ultrasonography
URL: http://www.pslgroup.com/dg/22E556.htm
Doctor's Guide
October 7, 2008

CHICAGO -- October 7, 2008 -- A comparison of 2 diagnostic methods used to detect deep vein thrombosis (DVT) of the lower extremities indicates that a simpler method, with wider availability, has rates of DVT detection that are equivalent to a more complex method, according to a study in the October 8 issue of the Journal of the American Medical Association.

The advantages of whole-leg ultrasonography include the ability to exclude isolated calf DVT, allowing for 1-day treatment of all patients, without additional testing. Conversely, it needs top-quality ultrasound equipment and experienced operators; therefore, it is often unobtainable after hours and during the weekends.

Despite the lack of definite evidence, whole-leg ultrasonography is thought to be better than serial 2-point ultrasonography, and as a consequence, many patients with suspected DVT need to wait hours or even days before whole-leg ultrasonography is obtained and are frequently administered anticoagulants in the meantime, according to background information in the article.

Enrico Bernardi, MD, Civic Hospital, Conegliano, Italy, and colleagues conducted a study to determine if the 2 diagnostic strategies are equivalent for the treatment of patients with suspected DVT of the lower extremities.

The randomised, multicentre study included 2,098 outpatients with a first episode of suspected DVT of the lower extremities. Patients were randomised to undergo 2-point (n = 1,045) or whole-leg (n = 1,053) ultrasonography.

Of patients in the 2-point strategy group, the incidence of confirmed symptomatic venous thromboembolism (VTE) during the 3-month follow-up period was 0.9% (7/801 patients). Of patients randomised to the whole-leg ultrasonography method, the incidence of confirmed symptomatic VTE during the follow-up period was 1.2% (9/763 patients).

"The observed difference between the 2 groups in terms of symptomatic VTE at the end of the 3-month follow-up period was 0.3%, which is within the chosen equivalence limit," the authors wrote.

"Either strategy may be chosen based on the clinical context, on the patients' needs, and on the available resources. [2-point ultrasonography plus D-dimer] is simple, convenient, and widely available but requires repeat testing in one-fourth of the patients. [Whole-leg ultrasonography] offers a 1-day answer, desirable for patients with severe calf complaints, for travellers, and for those living far from the diagnostic service, but is cumbersome, possibly more expensive, and may expose patients to the risk of anticoagulation."

In an accompanying editorial, C. Seth Landefeld, MD, University of California San Francisco, San Francisco Veterans Affairs Medical Center, San Francisco, California, and Stanford University, Stanford, California, comments on the findings of Bernardi and colleagues.

"How should clinicians approach patients with a possible first episode of DVT? Based on the available evidence, it would be reasonable to choose 2 tests initially -- a clinical prediction rule and D-dimer test, a clinical prediction rule and 2-point ultrasonography, or 2-point ultrasonography and a D-dimer test. If both tests are negative, DVT is effectively ruled out and anticoagulation can be withheld safely."

"If DVT is not ruled out, 2-point ultrasonography should be performed if not already performed. If DVT has neither been ruled out nor diagnosed by ultrasound, a second ultrasound should be performed 1 week later; if that ultrasound is negative for DVT, no further testing is indicated. The results of the trial by Bernardi [and colleagues] show that whole-leg ultrasonography has little advantage, unless a course of anticoagulant therapy for isolated calf DVT is preferable to repeating 2-point ultrasonography a week later."

SOURCE: Journal of the American Medical Association

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