Findings: The appendix is fluid filled and thick with hyperenhancing walls, periappendiceal stranding, appendicolith

Objectives:

• To review the anatomy of the appendix and how to identify it on CT

• To review the CT signs of uncomplicated appendicitis

• To review the complications of appendicitis and their imaging appearance

Protocolling:

• Contrast vs non-contrast CT – discuss oral and IV contrast use

Key Points:

• Identifying the appendix on CT:

  • Follow the colon from the rectum to the cecum

  • Identify the ileo-cecal valve (sail sign, fat density)

  • Appendix should arise from the cecum DISTAL (not necessarily inferior) to the IC valve, AND from the same side of the cecum as the IC valve

• CT signs of uncomplicated appendicitis

  • Dilated appendix (>7mm)

  • Hyper-enhancing, thick appendix wall

  • Focal cecal thickening (cecal bar sign, arrow sign)

  • Periappendiceal stranding

  • Appendicolith

• Complications to look for:

  • Perforation - extraluminal gas, discontinuous wall, fluid collection

  • Abscess (in the setting of perforation)

  • Thrombosis of portal venous system (SMV, portal vein)

  • Hepatic abscess

  • Fistula

Differential diagnosis:

• Tumors of the appendix

• Chronic appendicitis, as in Crohn appendicitis