Irritable Bowel Syndrome and Abdominal Pain

Irritable Bowel Syndrome (IBS) is a clinical condition characterised by altered bowel habits and abdominal pain without the presence of any underlying bowel pathology. It is a fairly common condition and reports by the National Institute of Clinical Excellence in the UK have estimated the prevalence in the general population to be between
10-20%. IBS is a disease of the young; it commonly occurs between the ages of
20 – 30 years.

In this article, we look at IBS in a bit more detail.

Causes of IBS

A clear cause of IBS has not been identified, but there are believed to be a number of factors that contribute to it. These include

  • Altered colon motility – This can either slow (causing constipation) or fast (causing diarrhea).
  • Bowel infection – IBS can occur after an episode of acute gastroenteritis or following Giardia lamblia infection.
  • Bacterial overgrowth in the small bowel.

Giardia lamblia on microscopy

Clinical features

Patients with IBS commonly complain of altered bowel habits. Episodes may alternate between constipation and diarrhea. Patients tend to want to open their bowels immediately after meals as well.

Along with the altered bowel habits, patients may also experience significant pain in the abdomen that is usually not localized to one point but rather widespread involving the entire abdomen. In addition, patients may also complain of increased flatulence and a feeling of abdominal bloating.

Clinical examination of the patient is usually normal.

Diagnosis of IBS includes the Rome III criteria which states that for a diagnosis if IBS to be made, the patient should have abdominal pain or uneasiness of a minimum of 3 days per month for at least 3 months along with 2 or more of the following –

  • Relief of pain after opening bowels
  • Onset of pain coincides with change in frequency of opening bowels
  • Onset of pain coincides with change in the appearance of the bowel motions

The National Institute of Clinical Excellence in the UK requires that the presence of the following features for more than 6 months can aid diagnosis of IBS –

  • Abdominal pain or discomfort
  • Bloating
  • Change in bowel habit

In addition, 4 patterns of IBS are identified based on the predominant symptom of either diarrhea being predominant or constipation, or whether it is a combination of both or
alteration between the two.


The diagnosis of IBS is primarily made through history from the patient. However, patients can have tests that will help rule out other ‘organic’ causes of the symptoms. In essence, if there are signs of weight loss, blood in the stools, iron deficiency anemia or a family history of a serious bowel illness, then alternative diagnosis must be
considered immediately so that appropriate treatments can be provided.

The tests that can be performed that will help rule out other causes include –

1. Blood tests – Helps to diagnose anemia. Thyroid function tests can help rule out hyperthyroidism which can cause diarrhea, but is not essential. Anti-endomysial antibodies helps detect underlying celiac disease.

2. Stool examinations – To look for infective pathogens that cause diarrhea. Giardia can be diagnosed this way as well.

3. Changing to a lactose free diet – If the symptoms subside, it could be that they were due to lactose intolerance and not IBS.

4. Barium studies – To diagnose inflammatory bowel disease which is an alternate cause for diarrhea.


The treatment of IBS is primarily supportive.

1. Dietary and lifestyle modification

In patients who predominantly suffer from constipation, a high fiber diet may be beneficial. However, this can increase the sensation of bloating that patients’ experience so may need to be tailored to each individual patient’s needs. However, while the theory of this sounds good, in practice its actual benefit is yet to be clearly demonstrated. If consumed, patients should consume soluble fiber like ispaghula rather than insoluble fibre like bran.

Certain foods that are preferably avoided include caffeine, alcohol, fizzy drinks and processed foods. Meals should be eaten on time without long gaps in between. Hydration is essential as well. In patients who have diarrhea as a predominant symptom, artificial sweeteners that contain sorbitol must be avoided.

2. Drug treatment

Drug treatments do not provide a cure, but only help in symptoms control.

In patients who have significant amount of abdominal pain, antispasmodic agents must be prescribed to help relive this. Laxatives are useful for patients with constipation as the predominant symptom.

However, lactulose must be avoided. In patients with diarrhoea, loperamide seems to be extremely effective.

It is important to bear in mind that different patients will respond differently to different laxatives, so treatment will need to be individualized for each patient.

In patients who have rather severe abdominal pain in whom normal antispasmodic agents are ineffective, tricyclic antidepressants or selective serotonin re-uptake inhibitors can be prescribed. However, if these are prescribed, patients need to be monitored for the development of side effects.

3. Cognitive behavioral therapy

This form of psychotherapy in fact helps patients manage the condition better, as a long history of IBS can have a significant impact on the quality of life of patients, thus causing mental stress. It has also been found to reduce the symptom severity as well, and is useful if medical therapy fails.

4. Complimentary treatments

There are no complimentary treatments that are effective in managing IBS, and are therefore not recommended.


IBS is not life threatening. Despite the symptoms, patients will still live the average duration of other people.


Irritable Bowel Syndrome is a chronic disorder characterized by abdominal pain, bloating and diarrhea. While there is no cure available, it is not life threatening and has no effect on the longevity of patients. Dietary modifications and drug treatments can help effectively control symptoms and help patients lead a good quality of life.


1. Irritable Bowel Syndrome NICE guideline – Retrieved from