title: Using clinical evaluation and lung scan to rule out suspected pulmonary embolism: Is it a valid option in patients with normal results of lower-limb venous compression ultrasonography?
abstract: BACKGROUND
  In patients with a low clinical probability of pulmonary embolism (PE) and a nondiagnostic lung scan, the prevalence of PE is theoretically very low. We assessed the safety and usefulness of this association for ruling out PE.
  
  
  METHODS
  We analyzed data from 2 consecutive cohort management studies performed in 2 university hospitals (Geneva University Hospital, Geneva, Switzerland, and Hospital Saint-Luc, Montreal, Quebec), which enrolled 1034 consecutive patients who came to the emergency department with clinically suspected PE. All patients were submitted to a sequential diagnostic protocol of lung scan, D-dimer testing, lower-limb venous compression ultrasonography (US), and pulmonary angiography in case of inconclusive results of noninvasive workup.
  
  
  RESULTS
  The prevalence of PE was 27.6%. Empirical assessment was accurate for identifying patients with a low likelihood of PE (8.2% prevalence of PE in the low clinical probability category). One hundred eighty patients had a low clinical probability of PE and a nondiagnostic lung scan. Among these patients, US showed deep vein thrombosis in 5. Hence, PE could be ruled out by a low clinical probability, a nondiagnostic lung scan, and a normal US in 175 patients (21.5%). The 3-month thromboembolic risk in these patients was low (1.7%; 95% confidence interval, 0.4%-4.9%).
  
  
  CONCLUSIONS
  Anticoagulant treatment could be safely withheld in patients with a low clinical probability of PE and a nondiagnostic lung scan, provided that the US is normal. This combination of findings avoided pulmonary angiography in 21.5% of patients with suspected PE in this series.
authors.affiliation: Medical Clinic 1, Geneva University Hospital, Switzerland. Arnaud.Perrier@medecine.unige.ch
authors.forename: A
authors.initials: A
authors.lastname: Perrier
authors.forename: M J
authors.initials: MJ
authors.lastname: Miron
authors.forename: S
authors.initials: S
authors.lastname: Desmarais
authors.forename: P
authors.initials: P
authors.lastname: de Moerloose
authors.forename: D
authors.initials: D
authors.lastname: Slosman
authors.forename: D
authors.initials: D
authors.lastname: Didier
authors.forename: P F
authors.initials: PF
authors.lastname: Unger
authors.forename: A
authors.initials: A
authors.lastname: Junod
authors.forename: J V
authors.initials: JV
authors.lastname: Patenaude
authors.forename: H
authors.initials: H
authors.lastname: Bounameaux
mesh_terms: D000328:Adult; D000368:Aged; D000792:Angiography; D001784:Blood Gas Analysis; D015331:Cohort Studies; D003937:Diagnosis, Differential; D004562:Electrocardiography; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010808:Physical Examination; D011237:Predictive Value of Tests; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D012306:Risk; D012307:Risk Factors; D013557:Switzerland; D014463:Ultrasonography