Computed tomography evaluation of variations in positions and measurements of appendix in patients with non-appendicular symptoms: time to revise the diagnostic criteria for appendicitis.

Purpose: To estimate the frequency distribution of different anatomical positions, and to measure the diameter, wall thickness, and length of appendix in patients with non-appendicular symptoms. Material and methods: This retrospective observational study was conducted among 1,575 patients, who had undergone computed tomography (CT) scan of abdomen for various non-appendicular signs and symptoms. Frequency of distribution of different anatomic locations and measurements of various morphologic parameters were recorded. Results: The most common location of appendix was retrocecal, followed by sub-cecal, post-ileal, and pelvic locations. The mean length of appendix was 66.7 mm (range, 6.3-123 mm), and the diameter was 6.3 mm (range, 2.8-11.3 mm). Diameter of > 6 mm was noted in 48.12% patients. The mean wall thickness was 2.37 mm, ranging 1.2-4.2 mm. The most common intra-luminal content was air-mixed with hypodense or hyperdense material observed in 70.5% of cases. Conclusions: Although an appendix with diameter less than 6 mm may be considered normal, a diameter above 6 mm has an overlap between a normal and inflamed appendix. Therefore, it should be considered in association with clinical and secondary findings to avoid overdiagnosis and unnecessary appendicectomies. We strongly recommend that diameter-based CT criteria to diagnose appendicitis should be revised and standardized.