Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome (IBS) is a chronic disorder of gut–brain interaction in which recurrent abdominal pain occurs together with changes in how often the bowels are opened and/or in the form of the stool.

It is also called “spastic colitis”, “sensitive bowel” or “irritable bowel” in everyday speech. But IBS does not require a “colitis” in the true sense — that is, inflammation in the bowel. Medically, IBS or irritable bowel syndrome are therefore the more accurate terms.

Is IBS common?

Yes. IBS is one of the commoner gastrointestinal problems in the population. It is described more often in women, but it can occur in both sexes and in different age groups.

The severity of the symptoms varies considerably from person to person.

What are the symptoms of IBS?

The most important symptom is recurrent abdominal pain. The pain can be related to opening the bowels and occurs together with changes in bowel habit.

Other common complaints:

• Bloating
• Wind
• Diarrhoea
• Constipation
• Diarrhoea and constipation alternating
• A change in the consistency of the stool
• A sudden need to open the bowels
• A sense of not emptying completely
• Mucus in the stool

Symptoms can increase for a period and then ease off for a long time.

What causes IBS?

IBS has no single cause. The changes now thought to matter are in the two-way communication between the gut and the brain.

In the development of the condition and in the appearance of the symptoms:

Changes in bowel motility → increased bowel sensitivity → changes in gut–brain communication → factors related to the microbiota and the immune system

can all play a part together.

In some people IBS begins after an episode of bowel infection. This is called post-infectious IBS.

Does stress cause IBS?

Describing IBS simply as “a condition caused by stress” is not accurate.

But because there is strong communication between the brain and the gut, stress, anxiety and sleep disturbance can increase the symptoms in some people.

That does not mean the patient’s complaints are psychological or imagined.

What types of IBS are there?

It falls into four main groups according to the characteristics of the stool:

• IBS-C: the type in which constipation predominates.
• IBS-D: the type in which diarrhoea predominates.
• IBS-M: the mixed type, with both constipation and diarrhoea.
• IBS-U: the unclassified type, not fitting any of the above.

The type of IBS can change over time.

How is IBS diagnosed?

The diagnosis of IBS is not simply a diagnosis of exclusion made on the basis that “all the tests were normal, so it must be IBS”.

A positive clinical diagnosis can be made from the characteristics of the patient’s symptoms, how long they have lasted, the examination findings and, where needed, a limited set of tests.

Standard symptom criteria are used in making the diagnosis today.

Is a colonoscopy needed to diagnose IBS?

Not every patient with IBS needs a colonoscopy.

Whether one is needed is decided according to the patient’s age, symptoms, family history, need for colorectal cancer screening, and alarm findings.

Which symptoms are not typical of IBS?

Some findings may call for another condition to be looked for. In particular:

• Obvious blood in the stool
• Unexplained iron deficiency anaemia
• Unintentional weight loss
• Newly started and steadily increasing complaints
• Fever
• A family history of colorectal cancer, coeliac disease or inflammatory bowel disease

should be assessed separately.

The presence of these findings does not necessarily mean there is a serious condition.

Are IBS and inflammatory bowel disease the same thing?

No.

In Crohn’s disease and ulcerative colitis there is genuine inflammation and tissue damage in the bowel.

In IBS there is typically no such structural inflammation. The word colitis in “spastic colitis” can therefore be misleading.

Why might faecal calprotectin be requested?

Faecal calprotectin can be used to help distinguish IBS from inflammatory bowel disease, particularly in some patients whose complaints include diarrhoea.

But a raised calprotectin on its own does not establish a diagnosis of Crohn’s disease or ulcerative colitis.

Can IBS and coeliac disease be confused?

Yes. Abdominal pain, bloating, diarrhoea and other IBS-like symptoms can occur in coeliac disease.

Blood tests for coeliac disease can therefore be done in suitable patients, particularly where diarrhoea-predominant IBS is being considered.

Starting a gluten-free diet before the coeliac tests are complete is not appropriate.

Why does bloating happen in IBS?

The amount of gas in the bowel may not explain it on its own. Increased sensitivity of the bowel to gas and to stretching, bowel motility, and the abdominal wall’s response to a gas load can all play a part in the sensation of bloating.

The complaint “I am very bloated” therefore does not always mean there is an unusual amount of gas in the bowel.

Does diet matter in IBS?

Yes. Certain foods can increase the complaints in particular people. But there is no single diet that can be applied to every patient with IBS.

Cutting a large number of foods out of the diet unnecessarily can lead to nutritional deficiency and a poorer quality of life.

What is the low-FODMAP diet?

FODMAPs are certain short-chain carbohydrates that ferment readily in the bowel.

In selected patients with IBS a low-FODMAP diet can reduce bloating, wind and abdominal pain in particular.

But the aim of this diet is not to ban all FODMAP-containing foods for life. Generally, after a short period of restriction, foods are reintroduced in a controlled way to establish the pattern of eating the person can tolerate. It is best carried out with a dietitian’s support where possible.

Should gluten be stopped in IBS?

Not every patient with IBS needs to give up gluten.

In particular, where coeliac disease is going to be investigated, stopping gluten before the tests can cause a false negative result.

Do probiotics help IBS?

Some probiotics may benefit some IBS symptoms; but not all products and bacterial strains have the same effect.

A general recommendation that “everyone with IBS should take a probiotic” is therefore not correct.

How is IBS treated?

Treatment is individualised according to the patient’s predominant complaint and the type of IBS.

Where needed, treatment can use:

• Dietary adjustments
• Soluble fibre
• Treatments for constipation
• Treatments for diarrhoea
• Antispasmodic medicines
• Certain medicines that modulate gut–brain interaction
• Dietary therapies in selected patients
• Physical activity
• Sleep and stress management
• Gut–brain focused psychological therapies

The same medicine or diet is not right for every patient.

Does IBS turn into cancer?

No. IBS is not cancer and does not turn into colon cancer.

Nor is IBS a condition that turns into Crohn’s disease or ulcerative colitis.

But an earlier diagnosis of IBS does not mean that new alarm symptoms appearing in later years should be attributed to IBS and disregarded.

Does IBS last a lifetime?

IBS can follow a chronic course, but the symptoms generally fluctuate.

In some periods the complaints become marked, while in others they can be very mild or not felt at all for a long time. With appropriate treatment the symptoms can be brought under substantial control in many patients.

In brief

IBS is a condition related less to structural damage in the bowel than to changes in gut–brain interaction, bowel motility and bowel sensitivity.

Abdominal pain + a change in bowel habit ± bloating is the typical picture.

IBS:

is not cancer → does not turn into cancer → does not mean there is necessarily inflammation in the bowel.

The diagnosis should be made correctly, and treatment arranged according to the patient’s type of IBS and predominant complaint.

Note: This information is provided for general patient education. Where there is blood in the stool, unexplained iron deficiency anaemia, unintentional weight loss, or new and steadily increasing bowel complaints, the symptoms need to be assessed rather than attributed to IBS alone.