Yee-Li Sun MD, Abstract Co-Author: Nothing to Disclose

Emily M. Webb MD, Presenter: Nothing to Disclose

Jesse L. Courtier MD, Abstract Co-Author: Nothing to Disclose

Joseph Stengel DO, Abstract Co-Author: Nothing to Disclose

Zhen Jane Wang MD, Abstract Co-Author: Nothing to Disclose

Fergus V. Coakley MD, Abstract Co-Author: Nothing to Disclose

Objective: To investigate the prevalence of intraluminal air in appendicitis and determine whether the presence or pattern of air within the appendix can be used as an aid in the diagnosis or exclusion of appendicitis at CT.

Materials and Methods: Following Institutional Review Board approval, we identified 100 consecutive patients (57 men and 43 women, mean age 38, range 18-77) who had a preoperative CT followed by a positive appendectomy for acute appendicitis between July 2002 and June 2007, and a control group of 100 consecutive patients (29 men and 71 women, mean age 39, range 18-82) with negative CT scans for appendicitis and no subsequent diagnosis of appendicitis during the study period. Scans were reviewed by two independent readers for presence and pattern of intraluminal air (diffuse, proximal, distal, scattered, stool-like, or air fluid level), outer wall to outer wall diameter, and for secondary signs of appendicitis. Proportions between groups were compared with the Fisher’s exact test. The student t-test was used to compare appendiceal diameter and frequency of secondary signs of appendicitis between groups.  

Results: 27/100 or 27% of patients with appendicitis had intraluminal air versus 66/100 or 66% of cases without appendicitis (p=0.0001). Intraluminal air was identified with almost perfect inter-observer agreement (Kappa=0.83). No significant differences in the patterns of intraluminal air were found between cases of appendicitis and controls. Among appendicitis cases, there was no significant difference in the appendiceal diameter in cases with intraluminal air (mean=12.8mm) versus without (mean=12.0, p=0.20), or number of secondary signs of appendicitis in cases with intraluminal air (mean=1.93) versus without (mean=1.86, p=0.78). No case of appendicitis had intra-luminal air in the absence of secondary signs of appendicitis.  

Conclusion: Intraluminal air was seen in 27% cases of appendicitis. The pattern of air was not helpful in differentiating a normal appendix from appendicitis. There was no significant difference in appendiceal size or number of secondary signs of appendicitis between appendicitis cases with and without intraluminal air.

Clinical Relevance: Although intraluminal air is sometimes assumed to exclude a diagnosis of appendicitis, it is actually a common finding seen in up to 27% cases at CT.

Sun, Y, Webb, E, Courtier, J, Stengel, J, Wang, Z, Coakley, F, The Prevalence and Patterns of Intraluminal Air in Acute Appendicitis at CT.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9015888.html