Anorectal disease (summary)

Radiopaedia • CC-by-nc-sa 3.0 • de
This is a basic article for medical students and other non-radiologists

Anorectal disease is a group of conditions that affect the anus and rectum. The most common conditions in this group include hemorrhoids, anal fissures, anorectal abscess and anal fistula.

Reference article

This is a summary article; we do not have a more in-depth reference article.

Summary

  • hemorrhoids
    • enlarged blood vessels around the anus and lower rectum
    • itch, inflammation and pain
    • may bleed
  • anal fissures
    • small tears in the anal mucosa
    • caused by constipation, diarrhea, anorectal inflammation
    • pain, bleeding and itching
  • anorectal abscess
    • abscess in close proximity to the anus or rectum
    • causes include inflammatory bowel disease, e.g. Crohn disease
    • imaging is useful in diagnosis and treatment planning
    • US and CT can be helpful
  • anal fistula
    • may form following an anorectal abscess
    • may be a complication of Crohn disease
    • MRI is the best test

Role of imaging

  • only for abscess and fistulae
  • make the diagnosis
  • plan treatment, e.g. image-guided drainage
  • assess response to treatment

Radiographic features

CT

Of limited use in perianal disease. May be useful to exclude an intra-abdominal abscess or collection, diverticular disease or perirectal disease.

MRI

Imaging findings are dependent on the disease. MRI is helpful for assessment of fissures, fistula and small, superficial abscesses, especially in Crohn disease.

Medical student radiology curriculum