Which imaging finding is consistent with a normal appendix on CT?

• A. Appendiceal diameter greater than 10 mm
• B. Wall thickening of the appendix
• C. Appendix wall less than 6 mm in diameter, with no wall thickening and no wall enhancement after contrast
• D. Peri-appendiceal fat stranding

Answer: (C)

On CT, a normal appendix should be small in caliber and without signs of inflammation. The key finding is a wall diameter under about 6 mm, with no wall thickening and no enhancement after contrast. When the appendix stays this small and shows no mural changes or enhancement, it suggests there’s no inflammatory process present. The absence of peri-appendiceal fat stranding or surrounding inflammatory changes further supports a normal appendix.

A diameter greater than roughly 6 mm (often cited as >6–7 mm) would raise concern for appendicitis, as would wall thickening or any enhancement of the wall after contrast, both of which indicate edema and inflammatory changes. Peri-appendiceal fat stranding is another sign associated with inflammation around the appendix, also not normal.