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Inflammatory Bowel Disease

Inflammatory Bowel Disease is a topic covered in the 5-Minute Clinical Consult.

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  • Inflammatory bowel disease (IBD) includes two separate clinical entities: ulcerative colitis (UC) and Crohn disease (CD). UC and CD are both uncontrolled immune-mediated inflammatory responses.
  • UC: relapsing and remitting course; inflammation is limited to the mucosal layer. UC always involves the colon (proctitis > left-sided colitis > pancolitis) ± extracolonic manifestations; hallmarks: bloody diarrhea and abdominal pain
  • CD: Transmural inflammation involving any part of alimentary canal, commonly affects small bowel (80% of cases), almost always involves the terminal ileum; hallmarks: skip lesions (spared areas of inflammation), fibrosis/strictures, intra-abdominal abscesses, and fistulas


  • Approximately 1.5 million North Americans are affected with IBD; increasing incidence over time, specifically in developed countries (1)
  • CD—20.2 per 100,000 person-years in North America and 12.7 per 100,000 person-years in Europe
  • UC—19.2 per 100,000 person-years in North America and 24.3 per 100,000 person-years in Europe (2)


Increasing, particularly in Europe:

  • CD—322 per 100,000 persons in Europe and 319/100,000 persons in North America
  • UC—505 per 100,000 in Europe and 249/100,000 in North America (2)

Etiology and Pathophysiology

  • Pathogenesis not well understood but multifactorial: genetic susceptibility; gut flora dysbiosis; external environment/geography; lifestyle and diet; and immune response
  • High levels of HLA II/activated macrophages secrete increased proinflammatory cytokines (IL-1, IL-6, IL-8, and TNF-α) in conjunction with decreased production of downregulatory cytokines (IL-2, IL-10, and TNF-β) (1).

There are 163 IBD-associated gene loci (110 for both UC and CD, 30 CD-specific, and 23 UC-specific).

Risk Factors

  • Cigarette smoking doubles risk of CD (1).
  • Age—bimodal peaks for UC (larger peak 30 to 40 and smaller peak 60 to 70); CD diagnosis peaks at 20 to 30 (1).
  • Alterations in gut biome or disruption in intestinal mucosa; diets high in sugar, omega-6 FA, unsaturated FAs, and meat may be risk factors (1).
  • Family history/genetic risk factors—up to 15% of patients have first–degree relative with IBD
  • More often in Ashkenazi Jews; less often in African American or Hispanic populations

General Prevention

No prevention of primary disease. Treatment focus is prevention of remission and comorbid conditions.

Commonly Associated Conditions

  • Extraintestinal manifestations: erythema nodosum, pyoderma gangrenosum, psoriasis, episcleritis, uveitis, scleritis, ankylosing spondylitis, sacroiliitis, osteoporosis, nephrolithiasis, DVT, primary sclerosing cholangitis ± cirrhosis, cholangiocarcinoma, chronic bronchitis, bronchiectasis, malabsorption, nutrition/vitamin deficiency
  • Metastatic CD, colorectal cancer (CRC)

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Stephens, Mark B., et al., editors. "Inflammatory Bowel Disease." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688193/all/Inflammatory_Bowel_Disease.
Inflammatory Bowel Disease. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688193/all/Inflammatory_Bowel_Disease. Accessed April 24, 2019.
Inflammatory Bowel Disease. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688193/all/Inflammatory_Bowel_Disease
Inflammatory Bowel Disease [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 April 24]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688193/all/Inflammatory_Bowel_Disease.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Inflammatory Bowel Disease ID - 1688193 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688193/all/Inflammatory_Bowel_Disease PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -