Appendiceal and peri-appendiceal air at CT: Prevalence, appearance and clinical significance

Aim: Appendiceal air has been reported as both a sign of appendicitis and of a normal appendix both at plain radiography and computed tomography (CT), It is the aim of this investigation to determine the prevalence, range of appearances, and significance of appendiceal and peri-appendiceal air at CT, Patients and Methods: Appendiceal CT scans of 100 patients with proven appendicitis and 100 patients with a normal appendix were reviewed for the presence of appendiceal and peri-appendiceal air, All cases mere correlated with surgical and pathological findings or clinical follow-up, Results: In 100 CT cases of appendicitis, appendiceal and/or peri-appendiceal air was present in one or more forms in 31% of cases, When present, it appeared as intraluminal air bubbles (38.7%) or air-fluid levels (22.6%), appendolith air (41.9%), intramural air (16.1%), peri-appendiceal air bubbles (12.9%), or extraluminal air-fluid level(s) (29.0%), Intramural and extraluminal air correlated with perforation in 60% and 100%, respectively, In 100 CT cases of a normal appendix, air was present in 57%, It was always intraluminal and appeared as small bubbles of air (52.6%), a tubular-shaped air collection (43.9%), or as an air-fluid level (3.5%), The appendiceal lumen was either airless (43%), or minimally (32%), moderately (18%), or completely filled with air (7%). Conclusion: Air is a common finding at appendiceal CT in both the normal and inflamed appendix, Intraluminal air is seen in both appendicitis and normal appendices, and cannot be presumed to indicate a patent lumen and thus a normal appendix, Appendolith, intramural and peri-appendiceal air appear diagnostic of appendicitis.