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What is IBS – the Rome III Criteria?

IBS tends to be characterized by either diarrhoea or constipation, or an alternation between the two complaints. Doctors refer to these IBS-D, IBS-C and IBS-A respectively. IBS-C, categorised by bouts of chronic constipation, is often accompanied by bloating and abdominal pain, too.

What all people with IBS have in common – whether theirs is characterised by constipation, diarrhoea or an alternation between the two – is that their symptoms match the Rome III criteria for IBS. This medical checklist used by doctors to detect irritable bowel syndrome states that the condition is a ‘recurrent abdominal pain or discomfort and a marked change in bowel habit for at least six months, with symptoms experienced on at least three days of at least three months’.

In addition to this, patients need to identify with at least two of these three statements in order to be considered an IBS sufferer:

  • Pain is relieved by a bowel movement
  • Onset of pain is related to a change in frequency of stool
  • Onset of pain is related to a change in the appearance of stool.

Irritable bowel syndrome takes different forms amongst its sufferers, and the symptoms of any two IBS sufferers can be quite different. Visit our page on IBS symptoms as well as our pages on the diagnosis of IBS to find out about which of your symptoms are most likely to be due to IBS and how doctors recommend making a diagnosis.

Causes of IBS range from post-infective to psychological, and the condition can be triggered by all sorts of other things too – see our page on triggers.

Of course, this means that there are different ways to treat irritable bowel syndrome. These include a wide range of medication as well as diet and other therapies, depending on the type and cause of the IBS. See our IBS treatment pages for more details.


If your GP believes that your symptoms may be a result of IBS, there are a number of diagnostic tests that they may use to confirm the diagnosis. These tests may be carried out at your GP surgery, or may require you to attend a specialist as an outpatient.

Diagnostic tests they might request include:

Keeping a Food and/or Stool Diary
Your doctor may want you to keep detailed notes of your food intake and bowel movements to document the symptoms and potential triggers accurately, in order to best help diagnose and treat your problem.

A test in which a small flexible camera is inserted down through your mouth to observe the inside of your upper digestive tract, including your oesophagus, stomach and upper small bowel in greater detail.

  • Small samples (biopsies) from the lining of the bowel wall can be sent to the laboratory to look for conditions such as coeliac disease (true allergy to wheat).
  • The biopsy samples can also be analysed directly by the doctor doing the test to check for lactose intolerance.

A test in which a small flexible camera is inserted up through your back passage to observe your large bowel (intestines) and the end of your small bowel in greater detail.

Flexible Sigmoidoscopy
This is very similar to a colonoscopy except that only the last part of the large bowel is examined.

Rigid Sigmoidoscopy
A test in which a very short rigid camera is inserted into your back passage to observe the anus and/or rectum in greater detail. The value of this test is limited as only a very small amount of the bowel is examined.

Blood tests
You may need to give a sample of blood to be tested for alternative conditions such as coeliac disease, IgA deficiency, thyroid disorders and inflammatory markers that could be causing your IBS-like symptoms.

Stool tests
You may need to provide your doctor with a sample of your stool so that they can observe stool quality and to test for infection or intestinal inflammation (faceal calprotectin).

Specialised tests
Depending on your precise symptoms, there are several other specialised tests that your doctor may require you to undergo. Some of the more common tests they may require include:

  • SehCAT study to test for bile acid malabsorption
  • Lactulose and lactose hydrogen breath tests to test for small-bowel bacterial overgrowth and lactose intolerance respectively
  • Small bowel physiology capsule (called ‘the Smart Pill’) to get a better picture of the conditions inside your digestive system, particularly your small bowel.
  • Several more tests can be useful too. Visit our specialised tests page
  • Depending on the results given by these tests, your doctor should be able to rule out other conditions such as inflammatory bowel diseases (like Crohn’s disease or Ulcerative Colitis), bile acid malabsorption, food intolerances, and of course, cancer. IN people with constipation, there may be a treatable cause which is not IBS so it is worth checking.

Specialised tests to diagnose IBS

As we learn more about IBS, we realise that many people have a clear and treatable cause for their symptoms. Depending on what you are suffering with, your doctor may, therefore, recommend more specialist tests. Many of these tests are not yet widely avaialable. At the London Gastroenterology Centre, we work hard to ensure we have the most up to date tests available so that we can pinpoint your problems as accurately as possible. Please note that we do not offer all tests as some tests are simply unreliable. We only offer tests which have a scientific basis.

Tests can be easily split into tests for diarrhoea and tests for constipation. Many people have both constipation and diarrhoea, so it is important for the doctor to assess which tests you might need.

Causes of for Diarrhoea

  • Bile salt malabsorption is the cause of diarrhoea in up to 20% of sufferers. It is, however, missed by many doctors. But it is simple to treat. The SehCAT scan is the simplest way to detect this problem.
  • Small intestinal bacterial overgrowth affects a sizeable number of people with diarrhoea. It is most common in people who have had abdominal surgery in the past. Also, as more people survive cancer, we are seeing this problem more often after radiotherapy for ovarian, uterine, colon and prostate cancer in particular. The test we use to detect this is the lactulose hydrogen breath test
  • A newly recognised problem is caecalmalfermentation. If you find that you run to the toilet three or four times each morning, but are fine for the rest of the day, it is quite possible you have this condition. The new Smart Pill test is a good way to diagnose this treatable problem. People with this condition often have alternating constipation and diarrhoea.
  • Did you know that almost all Asians and Black Africans have lactose intolerance? But it also affects 1 in 50 white British people. It may cause no symptoms at all, but it may also cause very dramatic wind, bloating and diarrhoea. There are two ways we use to diagnose it: the lactose hydrogen breath test and a specialised analysis of duodenal biopsy samples at endoscopy. Given that it can cause so much trouble and is so easy to diagnose, it is important not to miss this particular cause.

Causes of Constipation

  • Generalised slow colonic transit affects young women in particular. It can be diagnosed with a simple Xray called a colonic transit (Shapes) study
  • Disordered anorectal physiology occurs in many people for a variety of reasons. It generally means that when trying to open the bowels, the person accidentally holds him or herself back without realising it. The more they push, the worse the problem becomes. It is quite common, particularly in women after childbirth. There is a whole series of anorectal physiology tests including anorectal manometry, endoanal ultrasound and evacuating proctography. A combination of these tests may be needed to diagnose the problem. Fortunately, there are now good treatments available for this.

If you would like to access specialised tests for your problem, please contact us at the London Gastroenterology Centre. Call our office on 020 7183 7965 to make an appointment, or visit our contact page. Find out about our consultants here.

IBS Treatment

Patients often ask us how to cure IBS.

As yet, there is no known cure for IBS, so treatments are generally aimed at relieving symptoms and will differ depending on the issues you have been experiencing. But if you have a condition that mimics IBS, it may be completely reversible. For example an overactive thyroid can cause a diarrhoea predominant IBS picture but will respond very well to specific treatment for the thyroid.

The doctor will listen to you, assess your symptoms, as well as arranging appropriate tests or consulting the results of any tests already done, and your food and/or stool diaries if you have kept them. By studying all this information in detail your doctor can tailor a treatment plan to best suit your needs.

With the new tests our world class experts at the London Gastroenterology Centre have available, we can diagnose many people as having something which is actually not IBS and which can be cured. For example, if you have diarrhoea, you might be suffering from lactose intolerance, small bowel bacterial overgrowth of caecalmalfermenation. If you have constipation, the issue could be one of disordered anorectal function.

IBS treatment

Although we cannot tell you exactly how to cure IBS, we can almost certainly help you feel very much better.

Quite often the main problems you may experience are one or more of the following:

  • Constipation and/or Diarrhoea
  • Abdominal pain with or without hypersensitivity
  • Hyperventilation

Your doctor will prescribe treatments aimed at combating these particular symptoms.

Treatment for IBS comes in many different forms; it may involve taking medication to alleviate your symptoms, changing your diet to avoid aggravating your IBS, or undergoing therapy to improve relaxation and combat stress, a known trigger of the disease.

Some common treatments you may encounter include:

Treatments for constipation are designed to help you pass faeces, either by bulking up your stool, making it easier to pass, or by directly stimulating the bowel to contract.

Treatments for diarrhoea are designed to slow the passage of faeces through the intestines. Most anti-diarrhoea medications work directly on the bowel to slow its contraction.

As well as traditional painkillers, antispasmodics may be prescribed to help alleviate your IBS pain. Pain is usually somewhere in the abdomen, although sometimes it is felt in the chest or back. Antispasmodics work to reduce cramping in the bowel, which is a common source of pain in IBS.

Symptoms such as constipation can be eased by increasing fibre intake through your diet and/or with special high-fibre supplements. Some people actually do not respond well to a high fibre diet. These people need a low fibre diet together with special fibre replacement treatment. You may also be advised to follow a low FODMAP diet to ease your IBS symptoms, in addition to excluding foods that trigger your IBS.

Many IBS sufferers feel heightened pain sensations in their abdomen and digestive system. Your doctor may want to treat this with medication and/or certain types of other therapy.

Excessive or incoordinated breathing caused by stress of anxiety can lead to an excess of air in your digestive system, worsening your symptoms. Techniques and therapy aimed at reducing anxiety can aid in preventing this problem.

Psychological treatment
Stress can be a key trigger for IBS symptoms in many patients, so ensuring you remain relaxed and minimising anxiety can be a key way in minimising your symptoms. In addition to reducing stress, there are also a variety of ways in which psychological treatment can help you to gain control over your IBS, whether it be through medication, hypnotherapy or cognitive behavioural therapy (CBT).

Probiotics found in certain foods and supplements are ‘good’ bacteria that can help restore balance in your digestive system. They can reduce levels of harmful, disease-causing bacteria and inflammation and have been shown to be reasonably effective in reducing some patients’ IBS symptoms.

Diet and Exercise

There is no specific IBS diet but there is a clear connection between diet and IBS. Lots of sufferers are able to manage their symptoms very successfully themselves by altering their own diet: either eliminating certain foodstuffs or introducing new items to their regime.

Some straightforward tips for good digestion are:

  • Eat regular meals and don’t eat on the go. Take time over your meals
  • Try porridge or other oats for breakfast if you experience bloating and gas
  • A tablespoon of linseeds a day (not linseed oil) will also help reduce bloating – you can get them from health food shops
  • Drink eight glasses of water a day and limit caffeine to three cups a day (tea, coffee and fizzy drinks)
  • Try to eat no more than three portions (a portion weighs about 80g) of fresh fruit a day although you can eat plenty of vegetbales
  • Cut down on processed foods which can be difficult to digest
  • Limit your alcohol intake
  • Avoid sorbitol (found in artificial sweeteners, some sugar free chewing gums and mints) if you suffer from diarrhoea
  • Avoid foods made of insoluble fibre, like wholemeal bread and bran cereals, when your symptoms are worse. Soluble fibre is good for constipation, so up your intake of oats, nuts and seeds. Also look out for ispaghula (psyllium) powder in health food shops – it’s a soluble fibre supplement you can add to your food.
  • Isphagula causes bloating in some people, so another, less used husk called sterculia husk is another good one to take. This is sold as Normacol.

For a list of common IBS trigger foods, see our IBS triggers page.

A dietician might suggest that you follow the low FODMAP diet as a way to alleviate IBS symptoms and work out which foods need eliminating from your diet. FODMAPs are types of carbohydrates that are poorly absorbed into the small intestine. They’re thought to cause higher volumes of liquid and gas in the gut, leading to bloating and abdominal pain as well as other IBS symptoms. Since three of the major IBS trigger foods – wheat, lactose and fruit – are also high FODMAP foods, following the low FODMAP diet whilst keeping a symptoms diary can help you and your doctor or dietician diagnose the exact foods or food groups that are causing you trouble.

Exercise and IBS

Exercise is really important for digestion and it’s also great for stress-busting and promoting feelings of wellbeing. That’s not to mention what exercise does for the muscles and limbs.

Aim for five sets of thirty-minute sessions per week of non-competitive exercise. Walking, swimming, jogging and yoga are all superb options.

If you would like professional advice on how to help yourself, we are here to help you.

Help yourself

There are plenty of self-help routes for IBS sufferers. There are several ways that the condition can be managed from home, depending on your specific symptoms and triggers. For some, treating IBS symptoms with medicine (traditional or alternative) is the answer. For others, it’s dietary adjustments or lifestyle changes that bring about relief from the abdominal pain, bloating, constipation or diarrhoea. From probiotics to peppermint oil, there are pills, supplements and herbal remedies out there for every type of IBS.


Many sufferers of irritable bowel syndrome manage their symptoms through self-help. Managing and changing diet is probably the most common way that people deal with their symptoms themselves. With the help of a food diary, most IBS sufferers will start to see clear patterns in their symptoms, and will start to pinpoint their specific IBS triggers.

For in depth information about IBS and diet, read our article about it here

Natural remedies

There are also lots of herbs and supplements available on the high street, which can dramatically improve the various discomforts of IBS – bloating, gas and cramps as well as diarrhoea and constipation.

Peppermint is widely known for its therapeutic properties – it increases gut motility and eases abdominal cramping.
Similarly, a soothing chamomile tea can reduce gut spasms.
A handful of linseeds per day is often prescribed for its gentle laxative effects.

And this is only scratching the surface of possible alternative remedies for IBS symptoms.
Taking probiotics is another method of self-help for IBS that can be easily made part of a daily routine.

Click here to see our detailed page about natural remedies

Patients whose IBS seems to stem from stress or anxiety can also benefit from Meditation and self-hypnosis, whether in classes or from MP3s which you can download from the Internet that can help you detach from your worries and relax

We are available to see patients daily.

For a private consultation contact us on
020 7183 7965

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