Simpler diagnostic method may be as effective at detecting blood clot in the leg

CHICAGO – A comparison of two diagnostic methods used to detect deep vein thrombosis (DVT; a blood clot in a deep vein in the leg or thigh) 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 JAMA.

The imaging technique, compression ultrasonography, is a highly accurate method for the detection of DVT and has replaced other diagnostic methods in common practice. Two ultrasonography diagnostic methods often used are 2-point and whole-leg. With 2-point ultrasonography, compression is applied to two veins, and benefits include simplicity, reproducibility and broad availability (may be performed with virtually all ultrasound scanners, irrespective of age or model). “Its major limitation is the need to repeat the test once within 1 week in patients with normal findings at presentation to detect calf DVT extending to the proximal [near the point of origin] veins. Repeat testing may be safely avoided in patients with a normal D-dimer test [blood test used to help rule out active blood clot formation] at presentation,” the authors write.

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.

Enrico Bernardi, M.D., Ph.D., of the Civic Hospital, Conegliano, Italy, and colleagues conducted a study and found that of patients in the 2-point strategy group, the incidence of confirmed symptomatic venous thromboembolism (VTE; blood clots in the deep veins of the legs or in the lungs) during the 3-month follow-up period was 0.9 percent (7 of 801 patients). Of patients randomized to the whole-leg ultrasonography method, the incidence of confirmed symptomatic VTE during the follow-up period was 1.2 percent (9 of 763 patients).

(JAMA. 2008;300[14]:1653-1659)

Media Advisory: To contact Enrico Bernardi, M.D., Ph.D., email: enrico.bernardi@ulss7.it.

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