Inflammatory bowel disease - emergency medicine revision
Inflammatory bowel diseases (IBD) are chronic immune‑mediated disorders of the gastrointestinal tract driven by dysregulated mucosal immunity and altered intestinal microbiota.
The two principal diagnoses are ulcerative colitis (UC) and Crohn’s disease; about 5% of cases cannot be definitively categorised after standard assessment and are labelled IBD‑U (inflammatory bowel disease‑unclassified).
Emergency clinicians must recognise life‑threatening flares and complications, rapidly stabilise patients, initiate time‑sensitive treatments (particularly in acute severe UC), and escalate to specialist teams where indicated (NICE NG130, NG129, QS81).
Pathology and clinical differences
- Ulcerative colitis: continuous mucosal inflammation beginning in the rectum and extending proximally, limited to the colon and submucosa/mucosa.
- Typical presentation is bloody diarrhoea, urgency and tenesmus.
- Important complications include toxic megacolon, severe bleeding and increased long‑term colorectal cancer risk.
- Crohn’s disease: transmural, patchy (“skip”) inflammation that may affect any part of the GI tract.
- Common presentations are abdominal pain, non‑ or bloody diarrhoea, weight loss and malabsorption.
- Complications include strictures, obstruction, fistulae, intra‑abdominal abscess and perforation - often requiring cross‑sectional imaging and surgical or radiological intervention.
- IBD‑U: used when clinical, endoscopic and histological features cannot clearly separate UC from Crohn’s.
- Management may differ and will be specialist‑led.