Suspected acute appendicitis: nonenhanced helical CT in 300 consecutive patients

To determine the accuracy of helical computed tomography (CT) without the oral, intravenous, or rectal administration of contrast material in confirming suspected acute appendicitis.

Three hundred consecutive patients referred from the departments of surgery and emergency medicine were examined for suspected acute appendicitis by using thin-section nonenhanced helical CT. All transverse CT scans were obtained in a single breath hold from the upper abdomen (T12 vertebra) to the pubic symphysis with 5-mm collimation and a pitch of 1.6. All scans were obtained without oral, intravenous, or rectal contrast material. Criteria for diagnosis of acute appendicitis included an enlarged appendix (> 6 mm) and periappendiceal inflammation. CT diagnoses were recorded prospectively. Final diagnoses were established with the results of surgical or clinical follow-up or both.

There were 110 true-positive diagnoses, 181 true-negative diagnoses (63 of which were an alternative diagnosis correctly established prospectively), five false-negative diagnoses, and four false-positive diagnoses, which yielded a sensitivity of 96%, a specificity of 99%, and an accuracy of 97%.

Nonenhanced helical CT is a highly accurate technique for diagnosing or excluding acute appendicitis. Developing experience with the technique and understanding the subtleties of interpretation can further improve diagnostic accuracy.