Crohn's disease

What is Crohn's disease?

Crohn's disease is a long-term inflammatory bowel disease in which the immune system causes patchy inflammation that can reach deep into the bowel wall. It can affect any part of the digestive tract, most often the end of the small bowel and the colon. Symptoms flare and settle over the years.

Crohn's disease can affect the mouth, small bowel, and colon, and the healthy and inflamed sections often sit next to each other. The course varies widely, from quiet periods to occasional flares, and some people develop narrowing, fistulas, or abscesses.

What causes Crohn's disease?

The cause of Crohn's disease is not fully known. It results from an abnormal immune reaction in the digestive tract in people with a genetic predisposition, set off by an environmental trigger, with gut bacteria also involved. Smoking is a recognised risk factor and makes the disease worse.

• An immune reaction against the digestive tract
• Genetic predisposition
• A trigger in the environment
• Smoking, which worsens the course
• Gut bacteria playing a role in the reaction

What are the symptoms?

Crohn's disease commonly causes diarrhoea, cramping abdominal pain, tiredness, weight loss and poor appetite. Blood in the stool, fever during flares and anaemia can occur. Some people also have mouth ulcers or problems around the anus, such as fissures, abscesses or fistulas.

• Diarrhoea, sometimes with blood
• Cramping abdominal pain
• Weight loss and poor appetite
• Tiredness and anaemia
• Fever during flares
• Mouth ulcers and problems around the anus

When should I see a colorectal surgeon?

See a doctor about possible Crohn's disease if diarrhoea, abdominal pain or weight loss lasts more than a few weeks, or blood appears in the stool. Seek urgent care for severe pain with vomiting, which can signal a blockage, and for an abscess or fistula, heavy bleeding, fever, or being unable to eat or drink.

The warning signs below need prompt attention.

• A blockage with severe pain or vomiting
• An abscess or fistula
• Heavy bleeding
• Fever and inability to eat or drink
• Rapid weight loss

How is it diagnosed?

Crohn's disease is diagnosed by combining blood and stool tests, colonoscopy with biopsies, and imaging such as CT or MRI to see the small bowel and any fistulas. Capsule endoscopy is used in some cases. The tests also show how far the disease extends, which guides treatment.

• Colonoscopy with biopsies
• CT or MRI scans
• Blood and stool tests
• Capsule endoscopy in some cases
• Imaging for fistulas or narrowing

How is Crohn's disease treated?

Crohn's disease is treated first with medicines that reduce inflammation and calm the immune system, including biologic therapy, together with nutrition support and stopping smoking. Surgery is used for narrowing, a blocked bowel, fistulas, abscesses or disease that no longer responds to medicine. It treats complications and is not a cure.

• Anti-inflammatory and immune medicines
• Biologic therapy
• Nutrition support
• Surgery for strictures, fistulas, or blocked bowel
• Long-term surveillance and smoking cessation

What are the risks and complications?

Crohn's disease can cause bowel narrowing and blockage, fistulas and abscesses, and poor nutrition. Some people need more than one operation over their lifetime. Long-standing disease of the colon carries a slightly higher risk of bowel cancer, so surveillance colonoscopy is advised.

• Bowel narrowing and blockage
• Fistulas and abscesses
• Poor nutrition and delayed growth
• The need for more than one operation
• A slightly higher long-term bowel cancer risk