Crohn’s Disease

Characteristics of Crohn’s Disease

Any part of the intestine can be affected by chronic inflammation. It commonly affects young adults but can sometimes be first seen in the 7th decade. Any combination of areas may be present, the commonest being the final part of the small bowel and the anal region. It is sometimes associated with other conditions such as arthritis, eye symptoms, skin reactions and liver disease. Like ulcerative colitis, their presence reflects the disease severity. Its cause  is unknown but there is an increased risk in family members with the disease. 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 lower right side of the abdomen. Perianal disease can present with painful lumps, discharge and pain when going to the toilet.

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 budesonide, 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.  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.

Surgery is reserved for complications or failure of medical treatment.  Perianal disease requires drainage of abscesses, and fistulae may need cutting open or a long-term Seton drainage suture.

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 with early disease  are difficult to diagnose as there are many other digestive disorders which can mimic the symptoms. 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 but MRI scanning may ultimately be necessary.  In some, only a colonoscopy and ileoscopy will be all that is required. Diagnosis is confirmed with a biopsy but this is not always possible.