Clinical Utility of D-dimer in Patients With Suspected Pulmonary Embolism and Nondiagnostic Lung Scans or Negative CT Findings

The diagnosis of pulmonary embolism is difficult because the clinical diagnosis is nonspecific and all of the objective tests have limitations. The assay for plasma d-dimer may be useful as an exclusion test if results are negative. We conducted a prospective cohort study that evaluated the clinical utility (usefulness) of an automated quantitative d-dimer test in the diagnosis of patients with suspected pulmonary embolism. Consecutive eligible patients who had clinically suspected PE with nondiagnostic lung scans or negative helical CT scan of the chest results underwent d-dimer testing. The d-dimer results were negative in 11 of 103 inpatients (10.6%, 95% confidence interval [CI], 5.5 to 18.3%) and 7 of 22 outpatients (31.8%, 95% CI, 13.9 to 54.9%; p = 0.02). Measurement of plasma d-dimer is of limited clinical utility for inpatients with clinically suspected pulmonary embolism and nondiagnostic lung scans or negative helical CT results at a US academic health center.