Radiologic diagnoses of patients who received imaging for venous thromboembolism despite negative D-dimer tests

Objective The literature supports a negative D-dimer (−DD) excluding venous thromboembolic disease (VTE) in low-risk patients. We determined the radiologic diagnoses in patients where imaging was ordered despite a −DD. Methods This is a retrospective chart review of patients with a −DD (Tinaquant; Roche Diagnostics, Mannheim, Germany) and a radiologic study within 48 hours, sought to determine radiologic diagnosis (primary outcome), treatment of VTE, and consensus diagnosis of acute VTE. Results Among 3462 DD tests, 1678 met the inclusion criteria. Of 1362 patients with DD values of 350 ng/mL or less, 166 (12.2%) had radiologic studies: 93.4% of the final radiologic diagnoses were negative for VTE, 3.6% were indeterminate, and 3.0% (1.0%-6.9%) were positive; 1.8% ultimately had a consensus diagnosis of acute VTE. In 316 patients with DD values between 351 and 500 ng/mL, 88 (27.8%) had radiologic studies: 95.5% were negative, 1.1% were indeterminate, and 3.4% (0.7%-9.6%) were positive. Conclusions Of patients who receive radiologic studies despite −DD tests, 3.0% have positive radiologic diagnoses for acute VTE; only 1.8% had acute VTE after the review of their hospital course.