D-dimer, the final degradation product of cross-linked fibrin, is typically elevated in patients with acute venous thromboembolism. With its high sensitivity and negative predictive value, D-dimer testing may have a role for ruling-out the diagnosis in patients with suspected deep vein thrombosis or pulmonary embolism. For this purpose, D-dimer testing has been integrated in sequential diagnostic strategies including those using pretest clinical probability assessment and imaging techniques. A large variety of assays are now available for D-dimer measurement, with different sensitivities and specificities for the diagnosis of venous thromboembolism. Attempts to standardize the various D-dimer assays have been made but without any definitive answers as yet. The diagnostic yield of D-dimer testing is affected not only by the choice of the appropriate assay but also by patient characteristics. As a consequence, the clinical usefulness of D-dimer testing for the exclusion of suspected venous thromboembolism should be carefully evaluated in special clinical settings.
Suspicion of venous thromboembolism (VTE) isa frequent clinical problem, and prompt recognition of the disease is mandatory. However, specific diagnostic tests, such as compression ultrasonography for deep vein thrombosis (DVT) and computed tomography or lung scanning for pulmonary embolism (PE), are expensive and not always readily available. Moreover, only 25% of the suspected VTE episodes are confirmed by objective testing. 1 To avoid unnecessary anticoagulant treatment and the associated risk of bleeding, it is therefore crucial to accurately identify the 75% of patients with symptoms prompting a suspicion of VTE who do not have the disease. In the past two decades, extensive research has been performed to develop easier and more cost-effective diagnostic strategies for VTE. 2 In this context, D-dimer (DD) represents a simple, relatively noninvasive test that may allow clinicians to exclude the disease without a requirement for further imaging tests in a substantial proportion of patients. 3 In this review, we describe the currently available assays for DD measurement and their performance in diagnosing VTE. The role of DD testing in patients with suspected DVT or PE is analyzed in the context of different diagnostic strategies and clinical settings.
D-DIMER: PATHOPHYSIOLOGYDD is the final product of the plasmin-mediated degradation of cross-linked fibrin. Its blood concentration depends on clotting activation with fibrin