Diagnosis

What is irritable bowel syndrome?

Irritable bowel syndrome (IBS) is a painful and upsetting disorder that interferes with the normal functioning of the large bowel, with symptoms such as pain or discomfort in the abdomen, bloating, an urgent need to empty the bowel, and changes in bowel habit such as diarrhoea.

Some facts about IBS

• IBS is common - it affects between 10 and 20 per cent of the general population.
• It most often occurs in young people between the ages of 20 and 30.
• IBS is twice as common in women as in men.
• IBS will often come and go throughout a person's life and can be painful and upsetting.
• The exact cause of IBS is unknown.

Diagnosing IBS

There are no specific tests to confirm IBS, so diagnosis is based on an analysis of symptoms. The NICE guideline provides guidance on the diagnosis of IBS for healthcare professionals. Patients are asked if they have had any of the following symptoms that have lasted for at least six months: changes in bowel habit (such as diarrhoea or constipation); pain or discomfort in the abdomen; a bloated feeling. 

If the symptoms have been present for at least six months the person should be assessed for IBS. Other specific symptoms also need to present for a positive diagnosis: either, abdominal pain or discomfort that goes away when the bowel is emptied; or, abdominal pain or discomfort with a change in how often the bowel is emptied or stools (faeces) that look different from usual.

In addition, the person will have two of the following symptoms: a change in how stools are passed (such as needing to strain, feeling a sense of 'urgency' or feeling that the bowel hasn't completely emptied); bloating, tension or hardness in the abdomen; a feeling that symptoms are worse after eating; the passing of mucus from the rectum.

If the person has abdominal pain, they should be asked if this pain is in one area or moves around the abdomen - in IBS, pain usually does not stay in one place.

Other symptoms may include faecal incontinence (having accidents that involve a leakage of faeces), tiredness, nausea, backache and bladder problems (such as passing urine frequently or experiencing a sense of urgency).

Ruling out other problems

If symptoms suggest the possibility of IBS, then some tests are necessary to rule out other problems. Blood tests will check for anaemia and general levels of inflammation in the body, and make sure that the person is not suffering from another gut disorder called coeliac disease.  

It is also important to rule out the possibility that symptoms are being caused by other illnesses that need specialist treatment, such as cancer or inflammatory bowel disease (IBD). 'Red flag' symptoms for these conditions include unintentional and unexplained weight loss, bleeding from the rectum, and a family history of bowel or ovarian cancer. People aged 60 or over should be asked if they have had a change in bowel habit that has lasted for more than six weeks in which they are producing looser stools or need to empty their bowels more frequently. A physical examination may be necessary to check for lumps in the abdomen or rectum. Women may also be offered a pelvic examination.