Simple ultrasound test diagnoses deep venous thrombosis

Simpler is better when it comes to ultrasound applications for detecting deep vein thrombosis of the lower extremities. An Italian study found no significant difference in diagnostic power for this indication between two-point compression ultrasound plus a D-dimer exam and the more complex whole-leg compression ultrasonography. The study was published in the Oct. 8 issue of the Journal of the American Medical Association.

Dr. Enrico Bernardi of the Civic Hospital in Conegliano, Italy, led a prospective, multicenter trial that evaluated 2098 outpatients with suspected DVT of the lower extremities. They were randomized to receive either two-point compression or whole-leg ultrasound imaging.

With two-point ultrasonography, compression is applied to two veins using virtually any commercial ultrasound system, according to Bernardi. The exam is simple and reproducible. Its main shortcoming, the need to repeat the test within a week to detect calf DVT extending to the proximal veins, can be overcome with a D-dimer test at the time of the ultrasound exam to rule out blood clot formation.

Whole-leg ultrasonography can exclude isolated calf DVT, allowing for single-day diagnosis and treatment of patients without additional testing, but it requires a high-performance scanner and a knowledgeable operator to perform effectively, Bernardi noted in the report. These requirements can lead to imaging delays, and patients are sometimes treated with anticoagulants unnecessarily, he wrote.

The trial results established that radiologists can avoid these problems with no loss of clinical accuracy by using the two-point ultrasound test.

For patients in the two-point ultrasound group, the incidence of confirmed symptomatic venous thromboembolism (VTE) during a three-month follow-up period was 0.9% (seven of 801 patients). For patients evaluated with the whole-leg method, the incidence of confirmed symptomatic VTE during the follow-up period was 1.2% (nine of 763 patients).

Bernardi and colleagues reported that the observed difference between the two groups in terms of symptomatic VTE at the end of the follow-up period was 0.3%, which was within the chosen equivalence limit.

"Either strategy may be chosen based on the clinical context, on the patient's needs, and on the available resources," Bernadi wrote.

For more information from the Diagnostic Imaging archives:

Combined approach proves optimal in treatment of extremity veins

Tc-99m-rtPA SPECT determines the age of deep vein thrombosis

Quick training boosts accuracy for residents assessing DVT