D-dimer: establishing a laboratory assay for ruling out venous thrombosis

Patients with venous thrombosis (DVT or PE) have elevated D-dimer, a break-down product of cross-linked fibrin. The determination of D-dimer levels is both a diagnostic and a cost savings tool to rule out VTE. The assay can be used to eliminate those individuals without VTE, but with low or moderate clinical suspicion. The D-dimer assay is inexpensive, automated, has a rapid turnaround time, and uses standard blue-top tubes. After appropriate validation, the assay can be 100 percent sensitive in ruling out DVT or PE, but it will not confirm the presence of VTE as numerous other diseases and procedures can increase levels. The assay should not be used routinely on inpatients or surgery patients. Caution should be used when interpreting results from patients on anticoagulation therapy, since lower D-dimer levels may be found. If properly used, the D-dimer assay can save a healthcare facility significant money by eliminating imaging studies on patients with low or moderate suspicion of DVT or PE.