Measuring the Appendix — the Core Appendicitis Sign
A dilated, non-compressible appendix is the anchor CT finding.
- <6 mm: Normal diameter (placeholder reference range)
- >6-7 mm: Appendicitis cutoff (placeholder threshold)
- Present: Wall enhancement (placeholder finding)
- High: Sensitivity (placeholder estimate)
Caliper technique
Axial caliper measures outer wall to outer wall diameter.
Diameter alone rarely confirms diagnosis alone.
Periappendiceal Fat Stranding — Secondary Inflammatory Sign
Hazy increased density in RLQ fat signals surrounding inflammation.
- Reticular: Stranding pattern (placeholder descriptor)
- Proportional: Severity link (placeholder relation)
- RLQ: Location (placeholder region)
- Moderate: Specificity (placeholder estimate)
Fat density change
Inflammatory exudate raises fat attenuation locally.
Stranding severity tracks inflammation grade.
Sigmoid Wall Thickness — the Diverticulitis Anchor Sign
A thickened sigmoid colon wall points toward diverticulitis.
- <3 mm: Normal thickness (placeholder reference range)
- >4 mm: Diverticulitis cutoff (placeholder threshold)
- Sigmoid: Segment (placeholder location)
- High: Sensitivity (placeholder estimate)
Wall caliper
Measured perpendicular to bowel lumen wall.
Thickness scales with inflammatory severity here.
Diverticula — Outpouchings that Define the Disease
Small mucosal outpouchings along the sigmoid wall are pathognomonic.
- 3-10 mm: Typical size (placeholder range)
- Sigmoid-heavy: Distribution (placeholder pattern)
- Wall thickened: Inflamed variant (placeholder note)
- Perforation risk: Complication (placeholder note)
Outpouching appearance
Air or contrast filled sacs project from the wall.
Count and size rise with severity slider here.
RLQ vs LLQ — Location Settles the Differential
Quadrant location is the fastest differentiator on CT.
- RLQ: Appendicitis site (placeholder location)
- LLQ: Diverticulitis site (placeholder location)
- Uncommon: Overlap cases (placeholder note)
- Rare: Left-sided appendix (placeholder caveat)
Quadrant reasoning
Combine location with wall and fat signs together.
Slider blend shows both patterns coexisting visually.