Sensitivity and specificity of computed tomography and ultrasound for the prediction of acute appendicitis at King Fahad Specialist Hospital in Buraidah, Saudi Arabia

Objectives: To determine the sensitivity and specificity of computed tomography (CT) and ultrasound (US) in predicting acute appendicitis in relation to histopathology reports at King Fahad Specialist Hospital in Buraidah, Saudi Arabia.

Methods: A retrospective cohort study included 500 medical records of patients diagnosed with acute appendicitis upon admission to King Fahad Specialist Hospital, Buraidah, Saudi Arabia, between January 2015 and January 2017.

Results: Of the 200 patients, 187 (93.5%) were diagnosed with acute appendicitis by histopathology. Of these 187 patients, 57 (30.5%) underwent CT and 54 (29%) underwent US. Computed tomography correctly identified 86.0% of the patients as having acute appendicitis and incorrectly identified 14% as not having acute appendicitis. Similarly, US correctly identified 37% of the patients as having acute appendicitis, while the remaining 63% were incorrectly identified as not having acute appendicitis. Thirteen patients (6.5%) did not have acute appendicitis (confirmed by histology report). Six (46.15%) of these 13 patients underwent CT. Five of these 6 (83.3%) were incorrectly diagnosed with acute appendicitis by CT, whereas one of the 6 (16.7%) was identified as a true negative. On the other hand, US correctly identified 100% of the 13 patients as true negative.

Conclusion: Computed tomography was shown to have sensitivity 86% and a specificity of 16.7% for the diagnosis of acute appendicitis. On the other hand, US had a sensitivity of 37% and a specificity of 100%. Therefore, we conclude that if imaging needed to confirm the diagnosis of appendicitis, CT is the choice. Ultrasound can be used only to exclude gynecological disorders.