Ultrasound measures up in deep vein thrombosis diagnosis

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Two-point ultrasonography and whole-leg ultrasonography are equivalent when used for the management of symptomatic outpatients with suspected deep vein thrombosis (DVT) of the lower extremities, according to a study published in the October issue of the Journal of the American Medical Association.

Patients with suspected DVT of the lower extremities are usually investigated with ultrasonography either by the proximal veins (two-point ultrasonography) or the entire deep vein system (whole-leg ultrasonography). While the latter approach is thought to be better based on its ability to detect isolated calf vein thrombosis, the authors noted that it requires skilled operators and is mainly available only during working hours.

The researchers undertook a prospective, randomized, multicenter study to assess the incidence of symptomatic venous thromboembolism (VTE) during a three-month follow-up period in patients spared anticoagulation on the basis of a normal initial workup with either serial two-point ultrasonography plus D-dimer (two-point strategy) or whole-leg color-coded Doppler ultrasonography (whole-leg strategy).

Of the 2,465 eligible patients with suspected DVT, 2,098 patients met the inclusionary criteria, and were randomized to either the two-point strategy (1,045 cases) or the whole-leg strategy (1,053 cases).

Of the 1,045 patients randomized to the two-point strategy, the researchers found that 231 had abnormal findings at the initial diagnostic workup. A total of 217 patients had abnormal ultrasound findings at presentation, and 828 had normal test results and underwent D-dimer testing. D-dimer testing results were abnormal in 256 of 828 patients scheduled for repeat ultrasonography within one week. The remaining 814 patients, which included 572 patients with normal D-dimer and 242 patients with abnormal D-dimer and normal serial ultrasonography, were not anticoagulated and were followed for three months.

Of the 1,053 patients randomized to the whole-leg strategy, the investigators found that 278 had abnormal ultrasound findings at presentation. Of these, 213 patients had proximal DVT, 36 patients had isolated axial DVT and 29 patients had isolated muscular vein thrombosis. The remaining 775 patients with normal ultrasound findings were not anticoagulated and were followed up for three months.

The results showed that the two-point and whole-leg strategies are equivalent for the management of symptomatic patients with suspected DVT, according to the study.

“Either strategy may be chosen based on the clinical context, on the patients' needs, and on the available resources. The former is simple, convenient, and widely available but requires repeat testing in one-fourth of the patients. The latter offers a one-day answer, desirable for patients with severe calf complaints, for travelers and for those living far from the diagnostic service, but is cumbersome, possibly more expensive and may expose patients to the risk of (unnecessary) anticoagulation,” the authors concluded.