Crohn’s Disease

In Crohns’ disease, the entire intestinal tract can be affected with chronic inflammation.

Characteristics of Crohn’s Disease

  • The entire intestinal tract can be affected with chronic inflammation.
  • Any age is susceptible but a bimodal peak is present in the young adult and the 7th decade.
  • Any combination of areas may be present, the commonest being ileocaecal disease with or without perianal involvement.
  • Other systemic manifestations may occur including sero-negative arthritis, iritis, oxalate renal calculi, inflammatory skin lesions, and sclerosing cholangitis. Like ulcerative colitis, their presence reflects the disease severity.
  • Increasing scientific knowledge of Crohn’s disease is yielding associations with genetic loci. The CARD-2 gene may be mutated in certain families. This may disturb epithelial cell membrane integrity to allow transmigration of certain luminal bacteria and a granulomatous reaction.
  • Smoking is associated with increased risk and activity of the disease.

Presentation of Crohn’s Disease

  • Patients with severe colonic involvement are extremely unwell with anaemia, diarrhoea, and rectal bleeding.
  • Small bowel disease often has obstructive cramps with chronic diarrhoea.
  • The history may, on average, be 7 years before diagnosis.
  • Tenderness or a mass may present in the right iliac fossa.
  • Malabsorption can develop.
  • Perianal disease can present with abscesses and fistulae.
  • Recurrent suppurative infection and faecal soiling gives a poor quality of life.

Treatment of Crohn’s Disease

This depends on the site of the disease and its severity.

  • Prednisone 25-50mg daily is beneficial for acute disease.
  • Maintenance with 5-10mg daily may be required in a small subset of patients who relapse frequently.
  • Oral budenoside, a topical poorly absorbable steroid, can be used as an alternative in mild to moderate disease (3-9mg daily).
  • Azathioprine or 6-Mercaptopurine are used as steroid-sparing agents or monotherapy in resistant cases and have a 50% response.
  • Small bowel disease is maintained with Mesalazine granules 1-3gm/day, and colonic disease Mesalazine tablets 1-4 gm/day or Sulphasalazine 1-3 mg/day.
  • Surgery is reserved for complications (abscess, fistula, obstruction, bleeding).
  • Perianal disease requires drainage of suppuration, antibiotics (Metronidazole, Ciprofloxacin) or a long-tern Seton drainage suture.
  • Severe malnutrition may require TPN or an elemental diet.
  • Severe fistulous disease may respond to the anti-TNF antibody Infliximab. Fistulae will close in about 70% of patients. Treatment is expensive, costing about $12,000 for 3 infusions over 12 weeks. Maintenance therapy may be necessary.

Prognosis of Crohn’s Disease

  • Remissions and relapses are standard.
  • Patients with mild disease require minimal medical intervention. Others can run a severe or protracted course and eventually require surgery (resection, ileostomy, colectomy etc).
  • 70% of patients will have post-surgical recurrence by 7 years.
  • Mesalazine delays relapse.
  • Long term steroids require risk management for metabolic bone disease, vascular complications and diabetes.
  • Colonic disease requires surveillance colonoscopy after 10 years for dysplasia assessment.
  • The risk of colorectal carcinoma is increased.

Diagnosis of Crohn’s Disease

  • The diagnosis is usually easy in the younger patient with chronic diarrhoea, weight loss and abdominal pain.
  • Many patients do not have classical symptoms and are difficult to diagnose.
  • Stool microscopy and culture, FBC, CRP and ESR may not always be abnormal.
  • Small bowel barium follow-through is likely to detect the majority of cases of ileal disease.
  • In some, only a colonoscopy and ileoscopy will be accurate.
  • Apthous ulcers, deep fissuring ulcers, and inflammation with skip areas are characteristic.
  • Granulomas may not always be found on biopsy.
  • The diagnosis is then to be made on the clinical pattern of the disease.

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