Crohn's disease

Crohn's disease is a form of inflammatory bowel disease (IBD) that mainly affects the large and small intestines, but can appear anywhere between the mouth and anus. The most common place it occurs is in the ileum, the last part of the small intestine. Like ulcerative colitis, the other common type of IBD, it causes sores in the lining of the intestines and may lead to life-threatening complications. The main symptoms are severe diarrhoea, abdominal cramping and general tiredness. Crohn's disease is an autoimmune disease, which occurs when your body's immune system attacks your own tissues. There are several treatment options available, but this condition often requires lifelong management including medications, dietary measures and, in some cases, surgery. Crohn's disease may also be referred to as regional enteritis, ileitis, terminal ileitis, granulomatous enteritis and colitis.

Causes

The inflammation associated with Crohn's disease involves the full thickness of the gut wall. The actual cause of this inflammation is unknown, but a combination of factors are thought to be involved. The current thinking is that an inappropriate response of the immune system is probably central to the cause. Our bodies usually have trillions of 'good' bacteria living in our intestines, helping to break down and absorb nutrients. Parts of these bacteria pass through the lining and become a target for the immune system. Immune cells within the wall of the bowel are activated, releasing immune mediators such as tumour necrosis factor (TNF). This process is thought to be an integral part of how Crohn's disease occurs.

In Crohn's disease, the released immune mediators cause inflammation of the gut wall. 

Signs and symptoms

Gastrointestinal involvement

The symptoms of Crohn's disease can vary, depending on the extent, location and severity of the condition. A common area involved in Crohn's disease is the last part of the small intestine, called the terminal ileum. Involvement of the large bowel is also common, particularly in combination with terminal ileitis. Less prevalent patterns of involvement are isolated disease around the anus and the stomach and first part of the small intestine. All cases are different, but common symptoms are as follows:

• Diarrhoea - Crohn's disease causes the lining of your intestines to leak large amounts of water and salts, causing diarrhoea that may contain, blood, pus and mucus;
• Abdominal pain and cramping - pain can vary from mild to very severe. Inflammation and ulceration make it difficult for food to pass through the intestines, causing pain, especially after eating. Relief is often felt after a bowel movement;
• Nausea and vomiting;
• Weight loss and reduced appetite;
• Fever - this may be seen in severe cases of Crohn's disease. Associated with infection, it may be a warning of a complication such as an abscess;
• Blood in stools - inflammation and ulcerations in the bowel may often bleed on their own, though food passing over these areas may also cause bleeding, resulting in fresh blood in bowel movements;
• Anaemia - this is due to intestinal bleeding and a reduced ability to absorb iron, and;
• Ulcers - inflamed areas may develop ulcers, some of which may penetrate the entire thickness of the intestine wall. Mouth ulcers may also appear, as the mouth, being part of the digestive system, can be involved in Crohn's disease.

The gastrointestinal system. 

Symptoms from other areas of involvement

Depending on the severity of the condition, there is a wide range of other symptoms that may occur with Crohn's disease, such as:

• Arthritis - this is the most common extraintestinal manifestation. It generally involves large joints such as hips, shoulders and knees;
• Skin disorders - red nodules called erythema nodosum and pustular plaques that break down to ulcers known as pyoderma gangrenosum;
• Eye inflammation - inflammation of the uvea, the front part of the eye including the iris;
• Liver - the small bile ducts in the liver can scar, resulting in progressive liver failure. This is known as primary sclerosing cholangitis, and;
• Delayed growth in children.

Methods for diagnosis

Crohn's disease can easily be confused with other conditions that have similar symptoms, such as ulcerative colitis. Along with taking a full medical history, your doctor may want to conduct a range of medical tests in order to reach a correct diagnosis.

Medical history and physical examination

A full medical history will help your doctor discover whether your symptoms are consistent with inflammatory bowel disease. Your doctor will ask questions about the type and pattern of pain, the appearance and frequency of bowel motions and other related symptoms. A family history of bowel disease such as Crohn's may be discussed.

A physical examination will detect any tenderness in the abdomen, signs of changes in the anal region (fissures or abscesses) and any signs of inflammation.

Blood tests

These will check for infections, inflammation and internal bleeding. Levels of iron, proteins and certain minerals may also be checked.

Stool tests

Stool tests can help decide which type of bowel condition is present and also check for signs of parasites, blood, mucus, or infection.

Endoscopy

This test involves inserting a thin, flexible, lit tube with a camera (endoscope) into parts of the intestines through the mouth (gastroscopy) or via the rectum (colonoscopy). You will be given a mild sedative to help you relax during the procedure and often will be asked to do a bowel preparation prior to the test. The endoscope can take video, photos and tissue samples to provide a highly detailed view of the bowels and locate areas of inflammation.

Colonoscopy procedure. 

Biopsy

A biopsy of the wall of the gut is usually taken during an endoscopy. This sample can then be examined to look at the specific patterns of inflammation. For example, seeing inflammation that involves the full thickness of the bowel wall distinguishes Crohn's disease from other diseases such as ulcerative colitis.

Radiological tests

These tests can be helpful in the diagnosis of Crohn's disease and its complications. They are also often used to monitor your condition and how you are responding to treatment.

Barium testing

Barium testing involves drinking a chalky liquid called barium (a barium swallow) or having the liquid inserted in the rectum (barium enema). This allows structures such as the oesophagus, stomach, rectum and sigmoid colon to be clearly seen on X-ray. Strictures, inflammation, fistulas and other disorders may then be seen.

Magnetic resonance imaging

Magnetic resonance imaging (MRI) uses radio waves and magnets to create highly-detailed images of your internal organs. MRI may detect abnormalities and complications of Crohn's disease including abscesses or fistulas in the intestines, as well as changes in the bowel wall related to Crohn's disease.

Computerised tomography

A computerised tomography (CT) scan is a type of highly-specialised X-ray. A dye is ingested, injected or inserted into the rectum. Abnormalities of the intestines related to Crohn's and its complications can show up in a CT scan.

Ultrasound

Ultrasound uses soundwaves to create a picture of your internal organs. This will detect abnormalities such as abscesses, which can be complications of Crohn's disease.

Types of treatment

As there is no known cure for Crohn's disease, the main focus of treatment is to reduce the inflammation that causes your symptoms and lessen the risk of complications. In the long term, this can reduce flare-ups and greatly improve your quality of life. In the best possible case, this could lead to you becoming symptom-free for long periods of time (remission).

Lifestyle changes

Being diagnosed with Crohn's disease may make you feel helpless, but making simple changes to your lifestyle and diet may help you to manage your symptoms.

Diet

While there is no diet that has been shown to treat Crohn's disease, some people with Crohn's disease may find certain foods and drinks can make their symptoms worse during a flare-up. It is a good idea to keep a food diary to remind you which foods to avoid, as everyone is different, but some suggestions include:

• Dairy - limiting the amount of dairy products you eat may help with symptoms such as diarrhoea, abdominal cramps and gas. Some people with Crohn's disease are lactose intolerant, meaning they have a reduced ability to digest milk or other dairy products. However, your doctor may do further tests for this if it is suspected;
• Fatty foods - if you have Crohn's disease in your small intestine, you may have a reduced ability to absorb or digest fatty foods. Instead, these foods may pass quickly through your intestine, giving you diarrhoea. Choosing low-fat foods may help reduce this problem;
• Take care with high-fibre foods - in Crohn's disease, the small intestine can become narrow, making it harder for foods to pass through. Eating bulky, high-fibre foods may cause gas, abdominal cramps and diarrhoea. Raw fruits, vegetable and whole grains are high in fibre and may be easier to digest if cooked first;
• Eating bland or low-fibre, low-fat and non-spicy foods tends to be a safer option during a flare-up. 'Gassy' foods such as beans, cabbage, broccoli, raw fruit and vegetables, alcohol and carbonated drinks may need to be eliminated from your diet;
• Eat small meals often - instead of eating three or four large meals each day, it may be easier on your digestion to have five or six small meals, and;
• Drink lots of fluids - keep your fluids up by taking plenty of drinks throughout the day. Water is best, as tea and coffee contain caffeine, which can stimulate your intestines and may make diarrhoea worse. Fizzy, carbonated drinks often produce gas and can also make symptoms worse.

Smoking

Smoking increases your chances of developing Crohn's disease and tends to make all aspects of the condition worse. If you are a smoker and have Crohn's disease, you are more likely to have more flare-ups and also more likely to need surgery. By quitting smoking, symptoms of the disease can be alleviated.

Stress

Although stress does not actually cause Crohn's disease, it can make your symptoms worse and trigger flare-ups. At times of stress, your stomach empties more slowly, which increases acid production. The movement of food through your intestines may speed up or slow down, often causing cramping or pain. Stress is unavoidable in life, but finding ways to manage it can help. Even small amounts of exercise can reduce stress, ease depression and normalise bowel function. Learning how to relax by doing deep-breathing techniques can greatly reduce your stress levels.

Medication

Medication cannot cure Crohn's disease, but it can help ease many of its symptoms. In the best cases, these drugs can lead to a mostly symptom-free life and long-term relief in-between flare-ups. However, some medications can have side effects, so your doctor can advise you on the best choices for your particular case. Medications include:

• 5-Aminosalicylic acids (5-ASA) - these work by targeting the inflamed areas of your intestine to calm the immune response;
• Corticosteroids - these reduce inflammation by targeting your immune response. Due to side effects, these are usually a short-term measure;
• Immune system modulators (antimetabolites) - these drugs work by stopping your body producing substances that cause inflammation;
• Tumour necrosis factor (TNF)-alpha antagonists - these biological agents act by reducing the number of immune-response cells in your intestines;
• Antibiotics - these can help heal fistulas, abscesses and fight any other infections, and;
• Antidiarrhoeal medications - these are used to help prevent chronic or acute diarrhoea.

Surgery

If lifestyle and diet changes, medications and any other treatments do not give you any relief from symptoms, your doctor may consider surgery. A common surgery for Crohn's disease is bowel resection. Diseased sections of the bowel are removed and the healthy parts sewn together (anastomosis). Surgery can also drain abscesses, close fistulas and widen segments of the bowel that are too narrow (strictureplasty). Unfortunately, the benefits of surgery are often temporary, with symptoms eventually returning. Therefore, surgery is largely reserved for managing the complications of Crohn's disease.

Potential complications

Nutritional deficiencies

The lining of the small intestine is covered in tiny finger-like projections, called villi. These villi absorb nutrients, which then enter your bloodstream. Inflammation or surgery in the small intestine can reduce the amount of nutrients being absorbed, causing malnutrition, fatigue, delayed growth in children and anaemia. Medications can also reduce the body's ability to absorb some nutrients. You may need to get vitamin B12 injections on a regular basis.

Fistulas

These are openings between the intestines and other structures in the body such as the bladder, vagina and skin. A fistula may be detected as the cause for recurrent urinary tract infections, or an offensive vaginal discharge. They may heal themselves, but sometimes need surgery.

Toxic megacolon

This is a life-threatening condition in which the colon widens rapidly, accompanied by fever, shock, infection, rapid heart rate and tenderness of the abdomen. Surgery may be needed to remove part of the colon if the condition is severe.

Narrowing of the intestines

Inflammation can cause strictures, narrowing of the space in the intestines, which cause pain, discomfort and bloating. Surgery may be required. Bowel obstruction may result from strictures, usually presenting as severe abdominal pain with the inability to pass either gas or stools.

Prognosis

Crohn's disease is a lifelong condition with symptom-free periods that can vary in length, followed by flare-ups. While recurrence is common, some people can be symptom-free for decades, while others may experience symptoms every few months. Although there is no cure for Crohn's disease, there is a range of medication available, enabling most people to live a normal life. Surgery can sometimes help relieve serious symptoms that are not responding to medications, although it is often not permanently successful.

Prevention

Crohn's disease is a chronic condition with no known prevention or cure, but the severity of signs and symptoms may be reduced in some cases by carefully monitoring your diet, quitting smoking, exercising regularly and reducing your stress levels.