title: Value of short-interval computed tomography when sonography fails to visualize the appendix and shows otherwise normal findings.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the type and incidence of disorders revealed by short-interval computed tomography (CT) in patients with suspected appendicitis after graded compression sonography fails to reveal the appendix and shows otherwise normal findings.
  
  
  METHODS
  Computed tomographic findings and clinical courses were assessed retrospectively for 318 patients identified consecutively in a searchable database who met inclusion criteria specifying that sonography was the initial imaging examination for suspected appendicitis; sonography revealed nonvisualization of the appendix and otherwise normal results; and abdominopelvic CT was performed within 48 hours after sonography.
  
  
  RESULTS
  Of the 318 patients, short-interval CT revealed normal findings in 250 (78.6%). Appendicitis was revealed in 52 (16.4%) others, of whom 7 had perforation and all of whom had pathologic results confirming these CT findings. Important alternative diagnoses other than appendicitis were revealed in 16 (5.0%) others, including 2 (0.6%) who required urgent surgery and 14 (4.4%) who did not. No significant differences were observed between adult patients (>18 years) and pediatric patients.
  
  
  CONCLUSIONS
  Most short-interval CT scans in this clinical setting reveal normal findings, and relatively few disclose appendicitis or disorders that require urgent surgery. In view of concerns regarding radiation exposure associated with CT, these observations argue for the development of clinical triage methods that differentiate patients who are likely to benefit from short-interval postsonography CT from those who are not.
authors.affiliation: Department of Radiology, Stanford University School of Medicine, Stanford, California USA (B.R.S., J.S., R.B.J., E.W.O.); and Radiology Service, VA Palo Alto Health Care System, Palo Alto, California USA (E.W.O.).
authors.forename: Bhavya R
authors.initials: BR
authors.lastname: Shah
authors.affiliation: Department of Radiology, Stanford University School of Medicine, Stanford, California USA (B.R.S., J.S., R.B.J., E.W.O.); and Radiology Service, VA Palo Alto Health Care System, Palo Alto, California USA (E.W.O.).
authors.forename: Jessica
authors.initials: J
authors.lastname: Stewart
authors.affiliation: Department of Radiology, Stanford University School of Medicine, Stanford, California USA (B.R.S., J.S., R.B.J., E.W.O.); and Radiology Service, VA Palo Alto Health Care System, Palo Alto, California USA (E.W.O.).
authors.forename: R Brooke
authors.initials: RB
authors.lastname: Jeffrey
authors.forename: R Brooke
authors.initials: RB
authors.lastname: Jeffery
authors.affiliation: Department of Radiology, Stanford University School of Medicine, Stanford, California USA (B.R.S., J.S., R.B.J., E.W.O.); and Radiology Service, VA Palo Alto Health Care System, Palo Alto, California USA (E.W.O.). eolcott@stanford.edu.
authors.forename: Eric W
authors.initials: EW
authors.lastname: Olcott
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001064:Appendicitis / Q000000981:diagnostic imaging*; D001065:Appendix / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D005260:Female; D006801:Humans; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D011856:Radiographic Image Enhancement; D012189:Retrospective Studies; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D003287:Contrast Media; D007472:Iohexol
keywords: appendicitis; diagnostic imaging; gastrointestinal ultrasound; radiation protection; sonography; spiral computed tomography