Aim: To evaluate the role of a negative D-dimer assay in the initial management of patients with clinically suspected deep venous thrombosis (DVT), using colour Doppler ultrasound as the primary diagnostic technique.
Materials and methods: A double-blind prospective trial was performed on 143 patients with clinically suspected DVT. All patients underwent a D-dimer assay prior to anticoagulant therapy. DVT was confirmed or excluded by diagnostic colour Doppler ultrasound within 24 h of presentation.
Results: In nearly one-third of the cases (31.8%), Doppler ultrasound was positive. The D-dimer assay demonstrated a sensitivity of 97.7% with only one false-negative, but the specificity was low at 48.9% with 45 false-positive results. The positive predictive value for D-dimer assay was 48.8%, whilst the important negative predictive value was 98%.
Conclusion: If D-dimer was used to screen for DVT, and patients with negative results were not imaged, then the imaging workload could be reduced by 35%. In this study one small calf vein thrombus would have been missed by adopting this practice.Bradley, M. (2000). Clinical Radiology 55, 525-527.
Copyright 2000 The Royal College of Radiologists.