Crohn’s Disease

What is Crohn's disease?

Crohn's disease causes inflammation of the digestive system (gastrointestinal tract or gut). Any part can be affected (from the mouth, stomach, small intestine, colon, rectum to anus). However, it most commonly affects the small intestine (small bowel), the colon (large intestine) or the anus.

The disease is named after Dr. Burrill Crohn, who in 1932 was one of the first to describe patients with this condition.

Crohn’s is chronic (long-term). Many people have sustained periods of good health (remission) and times when symptoms are more active (relapses or flare-ups). There is currently no cure, but medicines and sometimes surgery can provide long periods of relief.

What is inflammatory bowel disease (IBD)?

Inflammatory bowel disease (IBD) describes diseases that cause inflammation in the bowel (colon and rectum). Crohn’s disease and ulcerative colitis are the two most important causes of IBD and can cause similar symptoms such as bloody diarrhoea.

It is important not to confuse IBD with IBS (irritable bowel syndrome), which is a different condition and does not cause bloody diarrhoea.

What causes Crohn's disease?

The cause is not known. Viruses, bacteria, diet, smoking and stress have all been suggested as possible triggers, but there is no definite evidence that any one of these is the cause.

About 3 in 20 people with Crohn's disease have a close relative who also has it, suggesting a genetic factor. One theory is that a germ triggers the immune system to cause inflammation in people who are genetically prone.

Does Crohn’s disease run in families?

Crohn’s can run in some families. Parents with IBD are slightly more likely to have a child with IBD.

The risk is generally small and is thought to be around 5% (about five out of every 100 children of people with Crohn’s may develop IBD in their lifetime). Genes are only part of the picture; environmental triggers also appear to play an important role.

How common is Crohn's disease?

Crohn’s disease affects about 1 in every 650 people in the UK, with around 115,000 people living with the condition. It can develop at any age but most commonly starts between 10 and 40 and affects women slightly more often than men.

It is more common in urban areas and in northern developed countries, though numbers are increasing in developing nations. It is more common in white people of European descent, particularly those of Ashkenazi Jewish ancestry.

Crohn’s has become more common in recent years, particularly among teenagers and children, but the reason is unknown. It is about twice as common in smokers and smokers tend to have more severe disease. The oral contraceptive pill and non-steroidal anti-inflammatory tablets have also been implicated as possible factors.

How does Crohn's disease cause problems with the gut?

The digestive system is a long tube from mouth to anus. Crohn’s causes ulceration and inflammation affecting digestion, nutrient absorption and waste elimination. It can affect any part of the gut but most commonly develops in the ileum (last part of the small intestine) or the colon. The ileum is affected in about half of cases. Mouth, oesophagus and stomach involvement is less common.

Inflammation is often patchy with normal bowel in between. It may be small or extend for a long distance. Crohn’s can also go deeper into the bowel wall. In about 3 in 10 cases it occurs only in the small intestine; in about 2 in 10 only in the colon; in other cases it involves different areas.

Inflammation can cause pain or diarrhoea (often when eating). Ulceration may bleed causing anaemia. Scarring can narrow the bowel causing a stricture. Inflamed areas can perforate leading to abscess or a fistula.

What are the symptoms during a flare-up of Crohn's disease?

During a flare-up, inflammation can cause one or more of the following:

• Abdominal pain (about 7 in 10 cases), often lower right abdomen. It can be mistaken for appendicitis. Sudden worsening can indicate complications such as abscess, perforation or obstruction.
• Diarrhoea (often first symptom). May be mild or severe. Mucus, pus or blood may be present. Urgency is common. Tenesmus (urge with little to pass) may occur.
• Tiredness/fatigue due to illness, weight loss, anaemia, or poor sleep from pain/diarrhoea.
• Malaise and sometimes fever.
• Mouth ulcers. Bowel ulcers may bleed causing anaemia.
• Loss of appetite and weight loss, including reduced absorption of nutrients.
• Anaemia from bleeding, reduced intake or poor nutrient absorption.
• Anal fissures, skin tags, fistulas and abscess. Sometimes Crohn’s presents only with anal problems.
• Problems away from the gut such as arthritis, skin rashes, uveitis (eye inflammation), and liver inflammation.

The reason for symptoms away from the gut is unclear; the immune system may trigger inflammation elsewhere. These problems often improve when gut symptoms settle, but not always.

What happens with Crohn's disease over time?

Crohn's disease is chronic and relapsing. People have flare-ups and remissions. Severity and frequency vary. The first flare-up is often the worst.

What are the possible complications of Crohn's disease?

Complications can occur, particularly if flare-ups are frequent or severe, and may require surgery:

• Stricture: scar tissue narrows the bowel and can cause blockage (cramping pain, nausea, vomiting, constipation, bloating, loud bowel noises). Often treated surgically (e.g. stricturoplasty).
• Perforation: a hole in the bowel wall causing leakage and infection/abscess; can be life-threatening and may lead to a fistula.
• Fistula: a channel between bowel and other structures (e.g. bowel-to-bowel, bladder, uterus). Perianal fistulas may open onto skin near the anus.
• Cancer: slightly increased colon cancer risk if severe Crohn’s has involved most of the colon for 8–10 years.
• Osteoporosis: increased risk linked to poor absorption in severe disease.

How is Crohn's disease diagnosed?

People with diarrhoea, abdominal pain and weight loss lasting several weeks may be offered tests, especially younger patients or those with a family history. Tests may include:

Blood tests and stool tests

Blood tests can show anaemia and inflammation. Stool tests can check bleeding/inflammation and exclude infection. A key stool test for inflammation is faecal calprotectin. If inflammation is confirmed, further tests may follow.

Endoscopy

• Upper GI endoscopy examines oesophagus, stomach and duodenum via a flexible camera through the mouth.
• Sigmoidoscopy or colonoscopy examines rectum and colon (and sometimes the ileum) via a scope through the anus. Endoscopy may be uncomfortable, so sedation is often used. Biopsies are commonly taken to confirm diagnosis.

Capsule endoscopy

A swallowable capsule camera takes pictures as it passes through the gut. Not offered everywhere and may not be suitable (e.g. if a stricture is suspected).

Barium X-ray

Now rarely used to assess small intestine or colon for inflammation.

MRI and CT scans

Increasingly used to assess location and extent of inflammation. MRI uses magnets and radio waves; CT uses specialised X-rays to build 3D images.

How is Crohn’s disease treated?

Treatment depends on severity, where inflammation is located, presence of complications, symptoms outside the gut, and which treatments have helped before. Options include:

No treatment

Some people with mild symptoms may not need treatment as symptoms can occasionally settle. If symptoms worsen, treatment can be reviewed.

Drug treatment

• Steroids (corticosteroids): reduce inflammation. Common examples: budesonide and prednisolone. Many improve within four weeks. Dose is reduced then stopped as symptoms settle. Steroid enemas/suppositories may help mild lower bowel flare-ups. IV steroids (e.g. hydrocortisone) may be needed for severe flare-ups.
• Immunosuppressants:
  • Immunomodulators (azathioprine, mercaptopurine, methotrexate) for more severe cases or when steroids haven’t helped.
  • Biological therapies (monoclonal antibodies) target immune chemicals such as TNF-alpha. Examples include infliximab (Remicade) and adalimumab (Humira), used when other treatments fail or in severe situations. These medicines have long-lasting effects and disease should be reassessed every 12 months to confirm ongoing need.
• Aminosalicylates (5-ASA): occasionally used in Crohn’s (more common in ulcerative colitis). Examples: mesalazine, olsalazine, balsalazide, sulfasalazine. Available as tablets, sachets, enemas or suppositories depending on inflammation location.
• Antibiotics: may be added if infective complications occur (e.g. infected fistula), such as metronidazole (Flagyl) and ciprofloxacin.

Dietary treatments

A strict liquid elemental diet may help some people (mainly children), with flare-ups settling within four weeks in some cases. A normal diet is gradually reintroduced. It may “rest” the gut. It is controversial but can be an alternative if medication has not worked or caused side effects.

Surgery

Modern medicines (including biological therapies) have improved control and extensive bowel resections are less common than before. However, surgery remains important and is often combined with medical therapies.

Around 7 in 10 people with Crohn’s may need surgery at some point. Surgery may be chosen when symptoms cannot be controlled medically, or urgently for severe blockage or perforation. Surgery is commonly required for complications such as fistulas, strictures and abscesses, including around the anus (e.g. abscess drainage).

General supportive measures

• Iron tablets for anaemia.
• Vitamins/nutrient supplements if absorption is poor.
• Parenteral nutrition (nutrition via vein) in severe cases.
• Painkillers during flare-ups.
• Hospital admission for IV fluids and intensive treatment in severe flare-ups.
• Vaccinations may be offered, especially if on immune-suppressing treatment.

Can I get pregnant if I have Crohn's disease?

Women with inactive Crohn’s usually have no more difficulty becoming pregnant than women without IBD. Active IBD can make pregnancy more difficult, particularly if underweight or eating poorly. Severe inflammation can also affect ovaries and cause adhesions that affect fallopian tubes. Pelvic surgery can reduce fertility due to adhesions.

Male fertility is generally not affected, although sulphasalazine may reduce fertility while taking the drug.

If planning pregnancy, discuss with your doctor. Extra folate may be needed and some medicines (e.g. methotrexate) must not be used during pregnancy.

What is the outlook (prognosis) for patients with Crohn’s disease?

Outlook varies depending on disease location and flare-up frequency/severity. Without treatment:

• About 3 in 20 have frequent and/or severe flare-ups.
• A few have only one or two flare-ups in their lives.
• Most fall in between, with flare-ups from time to time and long symptom-free spells.
• Rarely, a severe flare-up is life-threatening (e.g. perforation).

Modern immunosuppressant medicines have made a big impact. Reports suggest about 15 in 20 people remain in work ten years after diagnosis. In most cases, with treatment, Crohn’s is manageable enough for a near-normal life, though some people with severe disease experience a heavy burden.

Up to 8 in 10 people require surgery at some stage for complications. About half need surgery within ten years, commonly for strictures. Some require multiple operations. However, surgery rates may be falling due to modern treatments.

Am I at increased risk of cancer if I have Crohn’s disease?

People with Crohn’s affecting at least half of the colon surface are at slightly increased cancer risk. Those at increased risk are usually advised to have colonoscopy surveillance after about ten years of disease.

Surveillance includes colonoscopy with biopsies and often chromoscopy (dye spray). Based on findings, extent, polyps and family history, patients may be classified as low, intermediate or high risk.

Why is my doctor uncertain if I have Crohn’s disease or ulcerative colitis?

In about 1 in 20 people with IBD affecting only the colon, it is impossible to be certain whether it is Crohn’s disease or ulcerative colitis. This is more likely early after diagnosis. Over time, the true nature often becomes clearer.

If uncertain, the term Indeterminate Colitis or IBD Unclassified (IBDU) may be used. This generally should not affect management such as drug treatment.

Where can I get more information about Crohn’s disease or ulcerative colitis?

Crohn’s and Colitis UK

4 Beaumont House, Sutton Road, St Albans, Hertfordshire, AL1 5HH
Administration: 01727 830038
Information service: 0845 130 2233  |  info@crohnandcolitis.org.uk
Web: www.crohnsandcolitis.org.uk
A UK patient-orientated organisation with local branches and fundraising activity.

The Colostomy Association

Web: www.colostomyassociation.org.uk
Tel: 0800 328 4257
UK charity providing support and practical information for patients with a colostomy.

The Ileostomy Association

Web: www.the-ia.org.uk
UK charity providing support, fundraising for research, and information for patients with an ileostomy or ileoanal pouch.