The value of unenhanced CT in the diagnosis of acute appendicitis.

OBJECTIVE: To establish the accuracy of unenhanced CT in the preoperative diagnosis of acute appendicitis.

DESIGN: Accuracy study, prospective and blinded.

SETTING: The University Hospital.

PARTICIPANTS: 52 patients with clinical and laboratorial manifestations of acute appendicitis. CT diagnosis was made by: presence of an abnormal appendix, appendiceal calculi with pericecal phlegmon or alterations in the pericecal appendicular site and absence of signs that may lead to other diagnosis.

MAIN OUTCOME MEASURES: Overall accuracy, comparing the tomographic aspects with the intra-operative findings and pathological reports ("gold standard").

RESULTS: Acute appendicitis was confirmed in 44 cases. Efficacy was 92%, sensitivity was 91%, specificity was 100%, positive predictive value was 100% and negative predictive value was 67%.

CONCLUSIONS: Unenhanced CT presents a similar overall accuracy to that reported by other authors who studied enhanced CT diagnosis of acute appendicitis.