Differentiation of Nonperforated from Perforated Appendicitis: Accuracy of CT Diagnosis and Relationship of CT Findings to Length of Hospital Stay

Thomas A. Foley, BS, Frank Earnest IV, MD, Mark A. Nathan, MD, David M. Hough, MD, Henry J. Schiller, MD and Tanya L. Hoskin, MS
PURPOSE: To determine retrospectively the sensitivity and specificity of computed tomographic (CT) signs in differentiating acute nonperforated appendicitis from perforated appendicitis and to compare CT findings with the length of hospital stay.
MATERIALS AND METHODS: Institutional Review Board approval was obtained for this study, and patient informed consent was obtained for record review for research purposes. Two radiologists were blinded to patient identification but were informed that all patients presented to the emergency department with abdominal pain and underwent appendectomy. Radiologists independently reviewed CT images of 86 consecutive patients (45 males, 41 females; mean age, 33.7 years; age range, 8.2–87.1 years) who presented to the emergency department with acute abdominal pain, who underwent CT after initial emergency department assessment, and who underwent appendectomy within the subsequent 24 hours. Individual findings and confidence level for the diagnosis of perforated appendicitis were noted. Consensus interpretation was performed with a third radiologist. The consensus CT findings were correlated with the surgical and pathologic findings by using 2 or Fisher exact tests for univariate analysis and logistic regression for multiple variable analysis. Wilcoxon rank sum tests were used to assess the association between consensus CT findings and length of hospital stay.
RESULTS: Twenty-one (24%) of the 86 patients had appendiceal perforation. Extraluminal air and either moderate or severe periappendiceal inflammatory stranding were statistically significant independent predictors for perforation (P < .001). A focal defect in enhancing appendiceal wall was significantly associated with perforation (P < .001) and had a sensitivity of 58.8% and specificity of 85.7% on consensus review, with eight false-positive results. There was a strong association between the degree of periappendiceal inflammatory stranding and the length of hospital stay (P < .001).
CONCLUSION: Extraluminal air and moderate or severe periappendiceal inflammatory stranding are statistically significant independent predictors for appendiceal perforation and are associated with increased hospital stay.
(Radiology 2005;235:89.)