Pitfalls and mimickers at 64-section helical CT that cause negative appendectomy: an analysis from 1057 appendectomies.

Purpose: To determine the rate of negative appendectomy and clarify the causes of negative appendectomy in patients with clinically suspected acute appendicitis who had surgery after 64-section helical computed tomography (CT).

Material And Methods: A retrospective analysis of 1057 patients who had appendectomy after 64-section helical CT was performed to determine the rate of negative appendectomy. The 64-section helical CT examinations obtained with submillimeter and isotropic voxels in the patients with negative appendectomy were analyzed by two readers and compared to clinical, operative and histopathological reports, discharge summaries and original radiology reports.

Results: The negative appendectomy rate was 1.7% (18/1057). Appendix enlargement (>6 mm) and fat stranding were present in 17 (17/18; 94%) and 6 patients (6/18; 33%), respectively. In 13 patients (13/18; 72%) 64-section helical CT findings were consistent with acute appendicitis. Interpretive errors in original imaging reports were identified in five patients (5/18; 28%).

Conclusion: The preoperative use of 64-section helical CT results in a very low rate of negative appendectomy. Patients with negative appendectomy have 64-section helical CT findings consistent with a diagnosis of acute appendicitis in the majority of cases. Interpretive errors are less frequent.