Pitfalls in the CT diagnosis of appendicitis.

CT evaluation of appendicitis represents an increasingly common emergency room request. While the overall accuracy of CT is high, numerous pitfalls exist which may deceive radiologists, resulting in a missed diagnosis of appendicitis. The inflamed appendix may be unusual in its location, or may appear normal if only a small portion of the distal appendix is involved (tip appendicitis). In a patient with a history of appendectomy, inflammation of the appendiceal stump may be easily missed. Appendicitis may closely mimic small bowel obstruction, or gynaecological disease, especially after perforation has occurred. Even a misleading clinical history may lead the radiologist's eye astray. This pictorial review demonstrates these and other potential radiological pitfalls, and includes important points for the accurate diagnosis of appendicitis.