The role of D-dimer in the diagnosis of venous thromboembolism.

The diagnosis of venous thromboembolism remains a clinical challenge. D-dimer, a specific breakdown product of crosslinked fibrin, is a sensitive marker for acute thrombosis. Recent studies have demonstrated that D-dimer testing has a promising role as an exclusionary test in patients with suspected deep vein thrombosis or pulmonary embolism. However, a wide range of sensitivities and specificities has been reported for D-dimer assays because of inter- and intra-assay variations and differences in patient populations. New rapid D-dimer enzyme-linked immunosorbent assays and the whole blood agglutination assay SimpliRED (Agen Biomedical, Brisbane, Australia) D-dimer have high negative predictive values. Recent studies have shown that a normal result on a SimpliRED assay combined with a low pre-test probability or normal result on impedance plethysmography reliably excludes venous thrombosis. Latex agglutination assays are relatively insensitive as screening tests and should not be used. Management studies are underway and will further delineate the role of D-dimer testing in patients with suspected venous thromboembolism.