Appendicitis

Case Discussion

• 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