When Should We Order a CT Scan and When Should We Rely on the Results to Diagnose an Acute Appendicitis?

Objective: The objective of this study was to retrospectively analyze the last 100 consecutive emergency appendectomies performed in the authors' institution, which is a community-based teaching hospital, and look at the accuracy of the CT scan in the diagnosis of acute appendicitis. Design: Retrospective clinical study. Setting: A 600-bed community-based teaching hospital. Methods: The last 100 consecutive emergency appendectomies, which were performed at New York Methodist Hospital in 2004, were retrospectively analyzed. The collected data included the demographics of the patients, relevant history, physical examination, laboratory and radiological tests, and pathology results. The statistical analyses were performed using the JMP version 3.2 software (SAS Institute Inc., Cary, North Carolina). An alpha value of 0.05 was used in all statistical analyses, and p values were considered as being statistically significant at or below the alpha value of 0.05. Results: There was no statistically significant correlation between the acute appendicitis and some of the typical presenting symptoms and signs of acute appendicitis (rebound tenderness, low-grade fever, elevated white blood cell count, and anorexia). The sensitivity, specificity, positive predictive value, and negative predictive value of the CT scan in this retrospective analysis were 96%, 75%, 98.5%, and 50%, respectively, with an overall efficiency of 95%. However, the sensitivity, specificity, positive predictive value, and negative predictive value of the CT scan increased after reevaluation of the false-positive, false-negative, and inconclusive CT results by an experienced radiologist in a blind fashion (97%, 100%, 100%, and 71%, respectively). The correlation between the CT scan and the pathology result was statistically significant when the CT result was positive or negative (p = 0.0001). Conclusion: The CT scan is indicated when the clinical presentation is equivocal, and it will be helpful if the result is positive or interpreted as negative only by an experienced radiology attending.