Distal appendicitis: CT appearance and diagnosis.

PURPOSE: To determine the appearance of appendicitis in the distal part of the organ (distal appendicitis) on computed tomographic (CT) scans and to evaluate the accuracy of diagnosis based on CT findings.

MATERIALS AND METHODS: CT scans and medical records in 180 consecutive patients with proved appendicitis were reviewed. Fourteen had distal appendicitis with at least a 3-cm length of normal proximal appendix. Appendiceal CT scans and initial reports were reviewed retrospectively.

RESULTS: The proximal appendix was collapsed (n = 6) or was filled with contrast material (n = 6) or air (n = 2). Inflamed distal appendices averaged 13.2 mm in diameter and were associated with periappendiceal fat stranding (n = 14), adenopathy (n = 6), appendolith(s) (n = 4), or fluid (n = 2). Transition points consisted of a progressively narrowed appendiceal lumen and thickened wall (n = 5) or appendiceal diameter enlargement (n = 9). No cecal apical changes were seen. Scans in all 14 patients were prospectively interpreted as indicative of appendicitis, including 12 (86%) interpreted as indicative of distal appendicitis.

CONCLUSION: CT findings are useful for the accurate diagnosis of distal appendicitis. Visualization of the proximal appendix alone is insufficient to exclude distal appendicitis.