Inflammatory bowel disease (IBD) – overview

Inflammatory bowel disease (IBD): overview of ulcerative colitis and Crohn's disease

Inflammatory bowel disease (IBD) is the umbrella term for two autoimmune diseases causing persistent or relapsing inflammation of the digestive tract: ulcerative colitis (UC) and Crohn's disease (CD). In Denmark approximately 65,000 people live with IBD, one of the highest rates worldwide [1]. Onset is typically aged 15-35 but can occur at any age.

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The two forms - at a glance

Feature	Ulcerative colitis (UC)	Crohn's disease (CD)
Location	Colon only, from rectum upwards	Entire GI tract (mouth → anus)
Inflammation depth	Mucosa only	Whole bowel wall (transmural)
Distribution	Continuous	Patchy ("skip lesions")
Classic symptoms	Bloody diarrhoea, tenesmus	Abdominal pain, weight loss, fistulas
Complications	Toxic megacolon, colorectal cancer	Strictures, fistulas, abscesses
Smoking	Protective (paradoxical)	Worsens course
Surgery	Curative by colectomy	Not curative

→ For the full comparison: Crohn's disease vs. ulcerative colitis.

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Symptoms

Bowel symptoms:

• Chronic or bloody diarrhoea (>4 weeks)
• Abdominal pain, often cramping
• Tenesmus (painful urge to defecate)
• Rectal bleeding
• Black stool (rare, upper Crohn's)
• Weight loss, anorexia

Extraintestinal manifestations (up to 40 %):

• Joints (arthritis, sacroiliitis)
• Skin (erythema nodosum, pyoderma gangrenosum)
• Eyes (uveitis, episcleritis)
• Liver (primary sclerosing cholangitis, especially UC)
• Osteoporosis from corticosteroids

Alarm symptoms (acute):

• Severe rectal bleeding
• Fever >38.5 °C
• Signs of toxic megacolon (rare, life-threatening)
• Suspected perforation

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Diagnosis

1. History and clinical examination.
2. Blood tests: haemoglobin (anaemia), CRP, white cells, albumin, ferritin, B12, folate.
3. Faecal calprotectin - very sensitive marker of intestinal inflammation; used to distinguish IBD from IBS.
4. Stool studies - exclude infectious colitis (C. difficile, Salmonella, Shigella, Campylobacter).
5. Colonoscopy with multiple biopsies - gold standard. Assesses extent, severity, morphology.
6. Gastroscopy when upper Crohn involvement is suspected.
7. MR enterography or capsule endoscopy for small-bowel assessment (especially Crohn's).
8. CT abdomen in acute complications.

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Treatment - stepwise

Inducing remission:

• Mild-moderate UC: 5-ASA (mesalazine) topical and/or oral
• Moderate-severe: systemic corticosteroids (prednisolone)
• Severe acute: IV corticosteroids, possibly ciclosporin or infliximab

Maintaining remission:

• UC: lifelong 5-ASA
• CD: thiopurines (azathioprine) or methotrexate
• Biologics for severe or refractory disease: anti-TNF (infliximab, adalimumab), vedolizumab, ustekinumab, JAK inhibitors (tofacitinib, upadacitinib)
• "Treat-to-target" strategy aiming at histological healing [2]

Surgery:

• UC: total colectomy is curative - considered for medical failure or dysplasia
• CD: resection of complications (strictures, fistulas) - not curative; needed in 50-70 % over a lifetime [3]

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Monitoring and prevention

• Colorectal cancer screening: colonoscopy 8-10 years after disease onset, then every 1-5 years by risk.
• Vaccinations: influenza, pneumococcus, HPV, hepatitis B before biologic therapy.
• Bone density with chronic steroid use.
• Psychosocial support and dietitian.

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Treatment at Kirurgen.dk

We offer colonoscopy for primary IBD work-up and surveillance, gastroscopy for upper symptoms, and collaborate with gastroenterology and surgical departments for complex patients. See also: Ulcerative colitis, Crohn's disease, Crohn vs. ulcerative colitis, Microscopic colitis.

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References

1. Lophaven SN, Lynge E, Burisch J. The incidence of inflammatory bowel disease in Denmark 1980-2013. Aliment Pharmacol Ther 2017;45(7):961-72.
2. Turner D, Ricciuto A, Lewis A, et al. STRIDE-II: an update on the Selecting Therapeutic Targets in IBD (STRIDE) initiative. Gastroenterology 2021;160(5):1570-83.
3. Frolkis AD, Dykeman J, Negrón ME, et al. Risk of surgery for inflammatory bowel diseases has decreased over time. Gastroenterology 2013;145(5):996-1006.