Joseph Thomas Azok MD, Presenter: Nothing to Disclose

Sushilkumar K Sonavane MD, Abstract Co-Author: Nothing to Disclose

Thomas K. Pilgram PhD, Abstract Co-Author: Nothing to Disclose

Sanjeev Bhalla MD, Abstract Co-Author: Nothing to Disclose

Christine O. Menias MD, Abstract Co-Author: Nothing to Disclose

Risk factors for progression of acute appendicitis to perforation have not been clearly defined. The purpose of this study was to determine whether the finding of trapped air within an acutely inflamed but non-perforated appendix is a predictor of advanced appendicitis.

554 consecutive adult and pediatric patients with pathologically proven appendicitis over a 2-year period (Jan 1, 2007 – Dec 31, 2008) were retrospectively reviewed. A CT study was available for 354 patients. Patients with evidence of perforation (phlegmon, abscess, extraluminal gas, extraluminal appendicolith, or focal wall defect) on CT were excluded. The remaining cases were classified as either advanced or non-advanced appendicitis based upon the presence of perforation, gangrene, or necrosis either at surgery or on pathology. The CT images were reviewed by 2 radiologists for evidence of perforation and for the presence of trapped air within the appendix. Air within the appendix was classified as trapped if the air was present within the inflamed portion of the appendix. Differences in the prevalence of trapped air between the two groups were examined with a contingency table and patterns were tested for statistical significance with a chi-square test.

Of the 354 cases reviewed, 58 patients had CT evidence of perforation and were excluded. 79 patients had findings of perforation, gangrene, or necrosis either at surgery or on pathology and were classified as advanced appendicitis. 196 patients were classified as non-advanced. The mean ages of the two groups (advanced versus non-advanced) were 29 ± 21 years and 22 ± 15 years with comparable male to female ratios (42:37 vs. 116:80). The finding of trapped air within an inflamed but non-perforated appendix was present in 32% (25/79) of patients with advanced appendicitis versus 18% (36/196) in non-advanced appendicitis (p = 0.02).

Although a relatively insensitive finding, the presence of trapped air within the appendix occurred at nearly twice the rate in cases of advanced appendicitis versus non-advanced. These results suggest that trapped air within the appendix is a marker for advanced appendicitis.

Trapped air within an inflamed appendix is a CT sign of advanced appendicitis and should result in aggressive management to avoid appendiceal perforation and increased morbidity/mortality.

Azok, J, Sonavane, S, Pilgram, T, Bhalla, S, Menias, C, Trapped Air within an Inflamed Appendix Is a CT Sign of Advanced Appendicitis.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8003368.html