Mahesh Thapa MD, Presenter: Nothing to Disclose

Jenny McBroom BS, Abstract Co-Author: Nothing to Disclose

Joel A. Gross MD, MS, Abstract Co-Author: Nothing to Disclose

Edward Weinberger MD, Abstract Co-Author: Nothing to Disclose

In pediatrics, we wanted to evaluate the diagnostic accuracy of using a ≥ 6 mm diameter measurement of the appendix to identify appendiits.

In this pilot study, right lower quadrant ultrasounds for suspected appendicitis performed on 78 consecutive patients referred to the radiology department during on-call hours from September 2003 to April 2004 were retrospectively evaluated. There were a total of 29 boys and 49 girls, with ages ranging between 1.5 and 16 years.

Of the 78 patients in our study, the presumed appendix was found and measured in 57 cases. In 2 additional cases where the appendix was not visualized, a diagnosis of abscess secondary to perforated appendicitis was made. None of the 20 patients with maximum appendix diameter (MAD) of 6 mm or less had appendicitis with one exception where an appendix measuring 5.1 mm was correctly identified as perforated with abscess formation. With the exception of 2 cases, all 28 patients with MAD measurement greater than 7.5 mm had appendicitis. Of the 8 patients with MAD measurement between 0.60 and 0.75 cm, 4 had appendicitis, 1 had a Meckel’s diverticulum, and 3 had no appendicitis. None of the 3 cases with a normal appendix at surgery had strong secondary signs of inflammation.

Based on our initial pilot results, we suggest the following for diagnosing appendix in the pediatric population: If appendix ≤ 0.60 cm, negative for appendicitis with the caveat that incomplete visualization of the appendix and/or presence of secondary signs of appendicitis may reflect perforated appendicitis. A normal appendix may not be visualized by ultrasound If appendix ≥ 0.75 cm, appendicitis is likely present, although rare exceptions will occur. If 0.61 cm ≤ Appendix ≤ 0.74 cm, indeterminate zone. The ultrasound report can be further colored by the presence or absence of secondary inflammatory signs. (i.e. Indeterminate but likely negative in the absence of secondary signs) Now, we will evaluate > 2000 patients to verify our conclusions.

Close attention to secondary signs and size of the appendix, will significantly improve diagnostic accuracy of appendicitis.

Thapa, M, McBroom, J, Gross, J, Weinberger, E, Revised Ultrasound Size Criterion for the Diagnosis of Acute Appendicitis in the Pediatric Population.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5016190.html