Is it worth diagnosing and treating distal deep vein thrombosis? No.

The standard diagnostic approach to suspected deep vein thrombosis (DVT) is serial lower limb compression ultrasound (CUS) of proximal veins. Although it only assesses the proximal veins, withholding anticoagulant treatment in patients with a negative CUS on day 1 and after 1 week has been proved safe. In particular, studies evaluating CUS limited to the proximal veins showed a good safety profile with a pooled estimate of the 3-month thromboembolic rate of 0.6% (95% CI, 0.4-0.9%) in non-anticoagulated patients. However, performing two lower limbs CUS is cumbersome and expensive. Recently, studies using a unique complete (proximal and distal) CUS showed a similar pooled estimate of the 3-month thromboembolic rate (0.3%; 95% CI, 0.1-0.6%) but distal DVTs accounted for as many as 50% of all diagnosed DVTs in those series. Comparing these studies may suggest that systematically searching for calf DVTs potentially doubles the number of patients given anticoagulant therapy and entails a risk of over-treatment. Admittedly, performing calf CUS is highly useful in diagnosing other conditions such as popliteal cyst, hematoma or muscle rupture. Performing a CUS limited to the popliteal site in the presence of calf pain may be not well accepted by the patient. However, the advantage of calf CUS in diagnosing venous thromboembolism appears to be at the least debatable. Data suggesting that anticoagulation is indicated for distal DVT are limited, and realizing systematic distal CUS entails a risk of over-treatment. There is an urgent need for randomized trials assessing the usefulness of anticoagulant treatment in distal DVT.