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Two-point ultrasonography is as effective in diagnosing deep vein thrombosis as the more complex whole-leg method, according to a study published in  Journal of the American Medical Association.

Two-point ultrasonography and Whole –leg ultrasonography are used for detecting Deep Vein Thrombosis.   The researchers found that Two-point ultrasonography is as effective in diagnosing deep vein thrombosis as the more complex whole-leg method, , according to a study published in  Journal of the American Medical Association

Deep vein thrombosis is the formation of a blood clot ("thrombus") in a deep vein.  Deep vein thrombosis commonly affects the leg veins (such as the femoral vein or the popliteal vein) or the deep veins of the pelvis.  Deep vein thrombosis can cause potentially fatal pulmonary embolism and chronic pain, swelling, and difficulty walking.  

The two-point method is easy to learn and can be done on virtually any ultrasound scanner.  It does need to be repeated to confirm that any isolated calf deep vein thrombosis missed on the first exam hasn't spread.   The whole-leg method can definitively exclude isolated DVT in the calf in a single visit without additional testing.   Whole-leg ultrasonography would hold an advantage only if a course of anticoagulant therapy for isolated calf thrombosis was preferable to repeating two-point ultrasonography seven to 10 days later.  Whole –leg ultrasonography is more expensive than the two-point method

In Dr. Bernardi's study, three-month outcomes after whole-leg ultrasound were compared with those after compression ultrasonography of the common femoral and popliteal veins plus D-dimer testing for patients with normal ultrasonography and repeat ultrasonography one week later for those with a positive D-dimer test.  During three months follow up, the incidence of venous thromboembolism was 0.9 % with ultrasonography at the groin and back of the knee compared with 1.2% with a full groin-to-ankle scan.  In the study, the whole-leg method detected deep vein thrombosis more often than the two-point method (26% versus 22%, difference 4.3%, 95% CI 0.5% to 8.1%), which was entirely accounted for by isolated DVT in the calf.  The study was conducted by Enrico Bernardi, M.D., Ph.D. of the Civic Hospital and his colleagues.

But, treating clots restricted to the calf may not be necessary despite American College of Chest Physicians guidelines to the contrary, Dr. Landefeld said.The improved detection of isolated calf clots served as a rationale for whole-leg ultrasound, Dr. Bernardi's group said.

A more reasonable approach is to choose two readily available tests initially, coupled with two-point ultrasonography, Dr. Landefeld said.  Options are a clinical prediction rule to determine whether a patient is at risk and a D-dimer test to detect active clot formation.   Anticoagulation can be withheld safely if both are negative or, if not, patients can go on to two-point ultrasonography with a second ultrasound one week later, he said.

Whole-leg ultrasound may still be "desirable for patients with severe calf complaints, for travelers, and for those living far from the diagnostic service, but it is cumbersome, possibly more expensive, and may expose patients to the risk of (unnecessary) anticoagulation.

Source: Journal of the American Medical Association