title: Withholding anticoagulation after a negative computed tomography pulmonary angiogram as a stand-alone imaging investigation: a prospective management study.
abstract: BACKGROUND
  Accurate diagnosis of pulmonary embolism (PE) is essential and it is not clear whether a computed tomography pulmonary angiogram (CTPA) could be used as a stand-alone imaging investigation. The aim of the study was to test the accuracy of the clinical outcome of a negative CTPA as a stand-alone imaging investigation to exclude PE.
  
  
  METHODS
  Five hundred and thirty-four consecutive patients who had a CTPA for diagnosis or exclusion of PE were recruited from March 2003 to October 2004. Four hundred and ninety-four patients had a helical CTPA as a stand-alone imaging investigation for diagnosis or exclusion of PE. A 3-month post-CTPA follow up was carried out in all patients to establish the clinical outcome accuracy of a negative CTPA as a stand-alone imaging investigation.
  
  
  RESULTS
  There were 387 (78.3%) negative and 107 (21.7%) positive CTPA examinations. The average age of the patients was 57.16 years (standard deviation 18.57). Among those with a negative CTPA who survived, one patient had deep vein thrombosis and 342 patients had no evidence of an episode of venous thromboembolism or PE at the 3-month follow up. Thirty-eight patients died within the 3-month follow-up period and one patient's death was attributed to suspected PE. The negative predictive value of a CTPA is 99.5% (95% confidence interval 98.1-99.9%).
  
  
  CONCLUSIONS
  Helical negative CTPA examination excludes clinically significant PE as a stand-alone imaging investigation. Where concurrent deep vein thrombosis is suspected, lower limb needs to be imaged by ultrasound if the CTPA is negative.
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA. subramaniam.rathan@mayo.edu
authors.forename: R M
authors.initials: RM
authors.lastname: Subramaniam
authors.forename: D
authors.initials: D
authors.lastname: Blair
authors.forename: K
authors.initials: K
authors.lastname: Gilbert
authors.forename: G
authors.initials: G
authors.lastname: Coltman
authors.forename: J
authors.initials: J
authors.lastname: Sleigh
authors.forename: N
authors.initials: N
authors.lastname: Karalus
mesh_terms: D000328:Adult; D000368:Aged; D000792:Angiography / Q000379:methods; D000925:Anticoagulants / Q000008:administration & dosage*; D015331:Cohort Studies; D019468:Disease Management; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging* / Q000188:drug therapy; D014057:Tomography, X-Ray Computed / Q000379:methods*; D028761:Withholding Treatment
chemical_list: D000925:Anticoagulants