Exclusion of acute pulmonary embolism: Computed tomography pulmonary angiogram or D-dimer?

Chee Way Eng, G. Wansaicheong, S. K.J. Goh, A. Earnest, C. Sum

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Introduction: The aim of our study was to determine the accuracy of the D-dimer test in the exclusion of pulmonary embolism. Methods: In 2006, 446 patients at our hospital underwent computed tomography pulmonary angiogram (CTPA) for the exclusion of pulmonary embolism. We selected patients with a clinical suspicion of pulmonary embolism, and who underwent both a CTPA examination and a D-dimer test performed within a period of five days. Pregnant women, patients with an allergy to intravenous contrast and those who were on anticoagulant therapy were excluded. Based on our criteria, 219 cases were selected. D-dimer test was performed using an immunoturbidimetric assay. A cut-off value of 500 ng/ml was selected as the upper limit to exclude thrombosis. Results: There were 42 patients positive for pulmonary embolism on CTPA and all had elevated D-dimer values. There were 177 patients negative for pulmonary embolism on CTPA and 49 of them had normal D-dimer values. The sensitivity and specificity of the D-dimer test was 100.0 percent (95 percent confidence interval [CI] 91.6-100.0) and 27.7 percent (95 percent CI 21.2-34.9), respectively. The likelihood ratio for a positive test and negative test was 1.38 and 0, respectively. Conclusion: The D-dimer test is suitable for screening patients with a clinical suspicion of pulmonary embolism. The indiscriminate use of CTPA results in unnecessary testing and elevates healthcare costs. Clinicians are urged to give due consideration to a D-dimer test result prior to requesting a CTPA examination.

Original languageEnglish
Pages (from-to)403-406
Number of pages4
JournalSingapore Medical Journal
Issue number4
Publication statusPublished - 1 Apr 2009
Externally publishedYes


  • Computed tomography pulmonary angiogram
  • D-dimer
  • Pulmonary angiogram
  • Pulmonary embolism

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