Susan Sung MD, Presenter: Nothing to Disclose

Elizabeth P Ives MD, Abstract Co-Author: Nothing to Disclose

Haroon H. Durrani MD, Abstract Co-Author: Nothing to Disclose

Peter McCue MD, Abstract Co-Author: Nothing to Disclose

Ethan Joseph Halpern MD, Abstract Co-Author: Nothing to Disclose

To assess commonly accepted CT signs for the diagnosis of appendicitis in order to identify independent findings that predict appendicitis.

A retrospective database search identified 67 patients with a CT scan of the abdomen/pelvis and pathological evaluation of the appendix, including 41 with appendicitis and 26 with a normal appendix on pathologic examination. Each CT was reevaluated by three independent, blinded observers who evaluated appendix diameter, enhancement of the appendix, thickening of the appendix, presence of an appendicolith, infiltration of periappendiceal fat, focal cecal thickening, local lymphadenopathy, fluid collections, non-appendiceal bowel thickening, non-periappendiceal infiltration of fat and comparison of peri-appendiceal fat infiltration to thickening of adjacent bowel loops.

Mean diameter of the normal appendix (6.7 +/- 2.2mm) was significantly lower than that of the inflamed appendix (12.1 +/- 4.3mm), p 8mm (OR=34.8), enhancement of the appendix (OR=4.4), thickening of the appendix (OR=4.3), infiltration of periappendiceal fat (OR=5.5), focal cecal thickening (OR=5.1), non-appendiceal bowel thickening (OR=0.4) and non-periappendiceal infiltration of fat (OR=0.3). Of these variables, only appendix diameter and enhancement of the appendix were significant on multivariate analysis. An overall diagnostic impression based upon all secondary signs was less accurate than a diagnosis based upon appendix diameter alone (receiver operating characteristic analysis: Az=0.80 vs Az=0.91, p=0.02). Sensitivity/specificity of appendix diameter was 84%/87% using a cutoff between 8/9mm and 97%/48% using a cutoff between 6/7mm.

Appendix diameter is the best single diagnostic criteria for appendicitis on CT scan. A cutoff between 8/9mm provides the best balance of sensitivity/specificity, while a cutoff between 6/7mm improves sensitivity at the expense of specificity. The presence of appendiceal enhancement provides additional diagnostic information, but other secondary signs of appendicitis do not improve diagnostic accuracy.

Sung, S, Ives, E, Durrani, H, McCue, P, Halpern, E, Value of Secondary Signs in the CT Diagnosis of Acute Appendicitis.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4406249.html