Diagnosis of deep vein thrombosis.

Deep vein thrombosis (DVT) is part of the clinical spectrum of venous thromboembolism disease (VTE), whose estimated annual incidence rate is 1-2 episodes per 1000 individuals and represents the third leading cause of cardiovascular mortality in developed countries. Establishing an accurate diagnosis of DVT is essential for preventing acute complications (such as pulmonary embolism) and chronic complications associated with post-thrombotic syndrome. Currently, there are well-established diagnostic algorithms for lower extremity DVT, which include clinical probability models that help establish the risk of experiencing the disease based on the patients' history, clinical findings, D dimer measurements, fibrin degradation product tests with a high negative predictive value and imaging tests to confirm the diagnosis. Venous compression ultrasonography is currently the technique of choice because it is a non-invasive, easy-to-administer test that can make serial evaluations. There is much accumulated evidence that DVT can be safely ruled out in patients with a low or intermediate clinical probability and a negative D dimer (<500 ng/mL) without performing additional examinations. The consensus is not as clear about the need for a proximal or complete examination of the entire extremity. Other techniques may also be employed, such as magnetic resonance venography and venous phase computed axial tomography, although these should not be a substitute for compression ultrasonography as the initial diagnostic test. There are other special circumstances in which the diagnosis is more problematic and there are no diagnostic algorithms as consolidated, such as DVT during pregnancy, diagnosing rethrombosis and DVT that affects the upper extremities.