Inflammatory Bowel Disease

Basics

Description

  • Multifactorial, chronic, relapsing inflammatory diseases of intestines
  • Often has extraintestinal involvement
  • May present with exacerbation of existing disease or as initial presentation
  • Differentiation between ulcerative colitis (UC) and Crohn disease may be challenging and intermediate forms exist
  • Similarities of Crohn and UC:
    • Higher rate of colon cancer
    • Bimodal age distribution of onset, with early peak between teens and early 30s and 2nd peak about age 60
  • Differences between Crohn and UC:
    • Rectum almost always involved in UC with continuous inflammation proximally
    • Crohn can occur anywhere from mouth to anus, often with normal GI tract segments between affected areas
    • Crohn involves transmural inflammation, whereas UC is confined to submucosa
  • Pediatric considerations:
    • Can occur in 1st few years of life
    • Extraintestinal manifestations may predominate
  • Considerations in pregnant women:
    • Higher risk of adverse pregnancy outcomes, particularly in active disease

Etiology

  • Multifactorial origin including:
    • Genetic
    • Environmental (smoking, low fiber diet, NSAID use)
    • Altered microbiome
    • Immune
  • Crohn disease and UC are separate and heterogeneous entities with common genetic predisposition
  • A positive family history is common
  • Pathogenesis:
    • Gut wall becomes unable to downregulate its immune responses, ultimately resulting in chronic inflammation
  • No clear evidence for infectious etiology
  • Psychogenic factors may affect some exacerbations

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