Kimberly Anne Garcia MD, Presenter: Nothing to Disclose

J. Herman Kan MD, Abstract Co-Author: Nothing to Disclose

Chang Yu PhD, Abstract Co-Author: Nothing to Disclose

Marta Hernanz-Schulman MD, Abstract Co-Author: Stockholder, Biogen Idec Inc Stockholder, Bristol-Myers Squibb Company Stockholder, Healthways, Inc Stockholder, Pfizer Inc Stockholder, Tutogen Medical, Inc

Recent studies in adults have suggested that a nonvisualized appendix by CT excludes acute appendicitis. Children often have less intraperitoneal fat than adults and identifying a normal appendix becomes more challenging. The purpose of this study is to determine the diagnostic accuracy of CT studies in children when the appendix is not visualized

This study was approved by our IRB. 729 CT studies with IV contrast were performed for suspected appendicitis from 7/02 to 12/06. Of these, 171 reports stated the appendix was not visualized. These studies were reviewed by consensus by 2 pediatric radiologists blinded to the final radiology report and clinical diagnosis. 70 were excluded for lack of follow-up or because at review the appendix was visualized or a different cause for symptoms was found. The remaining 101 subjects (mean age 8.4 years, range: 1.0-17.4) constituted the study population and these studies were categorized as normal or abnormal based on the presence of indirect signs of appendicitis: bowel obstruction, right lower quadrant fluid or abscess, free air, or right lower quadrant fat stranding

Among 101 children with no visualization of the appendix, 7 had appendicitis and 94 did not. Using secondary signs CT correctly identified 6/7 with appendicitis (1 false negative), and 89/94 normals (5 false positives). Sensitivity, specificity, and accuracy for appendicitis was 86% (CI 42%, 100%), 95% (CI 88%, 98%), and 94%(CI 90%, 99%)

Our study shows that in pediatric patients, appendicitis cannot be excluded when the appendix is not visualized. Diagnosis becomes dependent on reliance on secondary signs of appendicitis, which can be less conspicuous in patients with paucity of intraperitoneal fat

A non-visualized appendix by CT does not completely exclude the possibility of appendicitis, and secondary signs assume greater importance in diagnosis

Garcia, K, Kan, J, Yu, C, Hernanz-Schulman, M, Diagnostic Accuracy of Pediatric CT for Appendicitis When the Appendix Is Not Visualized.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5013920.html