Overuse of computed tomography pulmonary angiography in the evaluation of patients with suspected pulmonary embolism in the emergency department

Acad Emerg Med. 2012 Nov;19(11):1219-26. doi: 10.1111/acem.12012.


Background: Clinical decision rules have been developed and validated for the evaluation of patients presenting with suspected pulmonary embolism (PE) to the emergency department (ED).

Objectives: The objective was to assess the percentage of computed tomographic pulmonary angiography (CT-PA) procedures that could have been avoided by use of the Wells score coupled with D-dimer testing (Wells/D-dimer) or pulmonary embolism rule-out criteria (PERC) in ED patients with suspected PE.

Methods: The authors conducted a prospective cohort study of adult ED patients undergoing CT-PA for suspected PE. Wells score and PERC were calculated. A research blood sample was obtained for D-dimer testing for subjects who did not undergo testing as part of their ED evaluation. The primary outcome was PE by CT-PA or 90-day follow-up. Secondary outcomes were ED length of stay (LOS) and CT-PA time as defined by time from order to initial radiologist interpretation.

Results: Of 152 suspected PE subjects available for analysis (mean ± SD age = 46.3 ± 15.6 years, 74% female, 59% black or African American, 11.8% diagnosed with PE), 14 (9.2%) met PERC, none of whom were diagnosed with PE. A low-risk Wells score (≤4) was assigned to 110 (72%) subjects, of whom only 38 (35%) underwent clinical D-dimer testing (elevated in 33/38). Of the 72 subjects with low-risk Wells scores who did not have D-dimers performed in the ED, archived research samples were negative in 16 (22%). All 21 subjects with low-risk Wells scores and negative D-dimers were PE-negative. CT-PA time (median = 160 minutes) accounted for more than half of total ED LOS (median = 295 minutes).

Conclusions: In total, 9.2 and 13.8% of CT-PA procedures could have been avoided by use of PERC and Wells/D-dimer, respectively.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Academic Medical Centers
  • Adult
  • Angiography / statistics & numerical data*
  • Biomarkers / blood
  • Cohort Studies
  • Emergency Service, Hospital*
  • Female
  • Fibrin Fibrinogen Degradation Products / analysis*
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Pennsylvania
  • Prospective Studies
  • Pulmonary Embolism / blood
  • Pulmonary Embolism / diagnosis
  • Pulmonary Embolism / diagnostic imaging*
  • Tomography, X-Ray Computed / statistics & numerical data*
  • Unnecessary Procedures / statistics & numerical data*
  • Urban Population


  • Biomarkers
  • Fibrin Fibrinogen Degradation Products
  • fibrin fragment D