Crohn's disease

Last edited 01/2021 and last reviewed 01/2023

Crohn’s disease is a chronic relapsing, remitting inflammatory disease of the digestive tract (1).

  • the aetiology of  the disorder is unknown
    • causes of Crohn's disease are widely debated
      • smoking and genetic predisposition are 2 important factors that are likely to play a role (6)
  • it is characterised pathologically by focal, asymmetric, transmural involvement of the bowel wall in a chronic inflammatory process with non-caseating granulomas (2).   

The granulomatous inflammation most frequently affects the terminal ileum but it may affect any part of the gastrointestinal tract and frequently affected areas are in discontinuity. There is a tendency to form complications such as strictures, abscesses and fistulae (4).

The disease may be classified according to the Montreal classification which considers the following:

  • age at diagnosis - <16 years, 17 to 40 years or >40 years
  • the disease location (terminal ileal, colonic, ileocolic, upper gastrointestinal)
  • the pattern of disease (inflammatory, fistulating, or stricturing) (3,4).

The inflammatory process in Crohn’s disease can involve the entire gastro intestinal tract. Inflammatory lesions in:

  • 15%–25% of patients are limited to the colon
  • 40%–55% are seen in the in the terminal ileum and the colon
  • 25%–40% are exclusively in the ileum
  • 1%–10% involves the esophagus, stomach, and proximal parts of the small bowel (5).

Typically people with Crohn's disease have recurrent relapses, with acute exacerbations interspersed with periods of remission or less active disease

  • whether a relapse refers to a recurrence of symptoms or the appearance of mucosal abnormalities before the development of symptoms remains the subject of dispute (6)
  • treatment is largely directed at symptom relief rather than cure, and active treatment of acute disease (inducing remission) should be distinguished from preventing relapse (maintaining remission).

Management options for Crohn's disease include drug therapy, attention to nutrition, smoking cessation and, in severe or chronic active disease, surgery.

The aims of drug treatment are to reduce symptoms, promote mucosal healing, and maintain or improve quality of life, while minimising toxicity related to drugs over both the short- and long-term

  • glucocorticosteroid treatment, aminosalicylate treatment, antibiotics, immunosuppressants and tumour necrosis factor (TNF)-alpha inhibitors are currently considered to be options for treating Crohn's disease
  • enteral nutrition has also been used widely as first-line therapy in children and young people to facilitate growth and development, but its use in adults is less common
  • between 50 and 80% of people with Crohn's disease will eventually need surgery for strictures causing symptoms of obstruction, other complications such as fistula formation, perforation or failure of medical therapy (6,7)