title: The non-diagnostic ultrasound in appendicitis: is a non-visualized appendix the same as a negative study?
abstract: OBJECTIVE
  The purpose of this retrospective study was to investigate outcomes in children who underwent a non-diagnostic ultrasound (US) evaluating for appendicitis and to identify predictors of a negative diagnosis.
  
  
  METHODS
  An IRB-approved retrospective chart review was performed on patients age 0-18, who underwent an abdominal US evaluating for acute appendicitis from 2004 through 2013. Clinical data and specified outcomes were recorded, and exams were categorized into non-diagnostic studies and further separated into studies where the appendix was non-visualized.
  
  
  RESULTS
  Of the 1383 studies included for analysis, 876 were non-diagnostic for acute appendicitis (63.34%) with 777 specifically because the appendix was non-visualized. Seven hundred forty of the 876 non-diagnostic studies and 671 of the 777 non-visualized studies were ultimately considered true negatives, corresponding to a negative predictive value (NPV) of 84.47 and 86.36%, respectively. In patients with WBC <7.5×10(9)/L, the NPV of non-diagnostic and non-visualized studies increased to 97.12 and 98.86%, respectively. Patients with WBC <11.0×10(9)/L have similarly high NPVs of 95.59 and 96.99% (non-diagnostic and non-visualized).
  
  
  CONCLUSIONS
  Based on the high NPV of a non-diagnostic US in children without leukocytosis, these patients may safely avoid further diagnostic imaging for the workup of suspected appendicitis.
authors.affiliation: Division of Pediatric, General, and Thoracic Surgery, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Cohen
authors.affiliation: Department of Surgery, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Jordan
authors.initials: J
authors.lastname: Bowling
authors.affiliation: Division of Pediatric, General, and Thoracic Surgery, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Midulla
authors.affiliation: Division of Pediatric, General, and Thoracic Surgery, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: Shlasko
authors.affiliation: Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Neil
authors.initials: N
authors.lastname: Lester
authors.affiliation: Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Henrietta
authors.initials: H
authors.lastname: Rosenberg
authors.affiliation: Division of Pediatric, General, and Thoracic Surgery, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Electronic address: aaron.lipskar@mountsinai.org.
authors.forename: Aaron
authors.initials: A
authors.lastname: Lipskar
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D001064:Appendicitis / Q000000981:diagnostic imaging*; D001065:Appendix / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D014463:Ultrasonography
keywords: Abdominal ultrasound; Appendicitis; Negative predictive value; Non-diagnostic ultrasound