2 Points About DVT Ultrasonography

The newer color-coded Doppler ultrasound scanners allow the evaluation of the entire deep venous system, from the groin to the ankle (whole-leg ultrasonography). With this strategy, color flow artifacts are exploited to enhance small vessel visualization, although vein compressibility still constitutes the main diagnostic criterion. The advantage of this approach is 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, especially in the everyday practice of ultrasound laboratories, based on the assumption that detecting isolated calf DVT is a clinically relevant issue. As a consequence, many patients with suspected DVT need to wait hours or even days before whole-leg ultrasonography is obtained and are frequently (unnecessarily) administered anticoagulants in the meantime.

Recent observations challenge this view and claim that prompt detection of calf DVT may not be as relevant as previously believed. Conversely, the systematic evaluation of the calf vein system may bring about a definite risk of overtreating thrombi that may otherwise heal spontaneously.

To test the hypothesis that the 2 diagnostic strategies are equivalent for the exclusion of a first episode of suspected DVT in symptomatic outpatients, we undertook a prospective, randomized, multicenter study assessing the incidence of symptomatic venous thromboembolism (VTE) during a 3-month follow-up period in patients spared anticoagulation on the basis of a normal initial workup with either serial 2-point ultrasonography plus D-dimer (2-point strategy) or whole-leg color-coded Doppler ultrasonography (whole-leg strategy).

Conclusion, both serial 2-point ultrasonography plus D-dimer and whole-leg color-coded Doppler ultrasonography represent reliable diagnostic options for the management of symptomatic patients with suspected DVT of the lower extremities. 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 1-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.

Study: Serial 2-Point Ultrasonography Plus D-Dimer vs Whole-Leg Color-Coded Doppler Ultrasonography for Diagnosing Suspected Symptomatic Deep Vein Thrombosis

Image from Massachusetts General Hospital Department of Radiology: Right lower extremity (A) transverse and (B) saggital images from color Doppler ultrasound demonstrates blood flow in the femoral artery but not in the common femoral vein (arrows). This is an indirect finding that suggests common femoral DVT