A 19-year-old female university student comes to see you. While on holiday over the summer she contracted Campylobacter gastroenteritis, which resulted in a two-week period of loose stools, abdominal pain and urgency, but after three to four weeks her bowel habit returned to normal. She is a keen sportswoman and high achiever academically.
Four months later she complains of episodic colicky abdominal pain, with bowel habit fluctuating between loose stools, perhaps three or four times a day and hard stools, which are difficult to pass. She says that when she is symptomatic she feels bloated and doesn’t feel like eating.
Since starting university, she has enjoyed her new life and denies any specific stresses. She is approaching end-of-term exams.
At initial review it seems likely that her symptoms reflect an episode of irritable bowel syndrome (IBS), perhaps provoked by the episode of Campylobacter and her subsequent change in lifestyle when starting university.
Before drawing a conclusion of IBS, it is important to explore whether she has any red-flag symptoms that should prompt further investigation. These red flags include a history of unexplained weight loss, rectal bleeding, family history of bowel or ovarian cancer, or, in patients over 60 years of age, change in bowel habit.
All patients with these symptoms should be asked directly about a family history of bowel or ovarian cancer. Bowel cancer is relatively common and having a second-degree relative who develops the disease over 60 years of age may not raise alarm. But the presence of bowel or ovarian cancer in any first-degree relative, or in a close family member under the age of 50, should suggest further investigation.
Significant unexplained weight loss is always a concern, and while it may occur at times of stress or lifestyle change it is unusual in adults and should make you consider further investigation.
Rectal bleeding is not normal and is not a feature of IBS. However, the nature of the bleeding is often a clue to the likely aetiology. Bright red rectal bleeding, often occurring after a hard, difficult-to-pass stool, limited to the tissue paper, often reflects a local anal cause, such as a fissure or haemorrhoids. Fresh blood mixed with loose mucous stool may reflect inflammation in the large bowel, whereas blood and clots in the bowl, mixed with the stool, may reflect an isolated cause higher up in the large bowel (such as diverticular disease or a polyp).
Before a diagnosis of IBS is made the patient should be examined to exclude abdominal and rectal masses and anaemia. Every person presenting with abdominal pain, bloating and change in bowel habit should undergo testing
to ensure they have a normal full blood count, inflammatory markers (commonly CRP or ESR) and coeliac serology.
Where available they should also undergo a faecal calprotectin test – normal calprotectin largely excludes inflammatory bowel disease. However, numerous factors can increase calprotectin, including excess alcohol, NSAID analgesia and resolving infection, so mildly abnormal results need to be interpreted with caution. Useful guidance on the appropriate interpretation of calprotectin is available online.1
The patient had no red-flag symptoms and her coeliac serology and blood tests were normal, as was her calprotectin.
In summary, the patient is a young woman with abdominal pain, bloating and change in bowel habit, in whom inflammatory or coeliac disease has been excluded. In the absence of red flags or other specific symptoms pointing to an alternative diagnosis, it is reasonable to make a firm diagnosis of IBS. A positive diagnosis is often enormously helpful for the individual and can lead to a better understanding of the condition and the factors likely to exacerbate it.
IBS is a descriptive term used for the collective symptoms that arise as a result of dysfunction of the interactions between the brain, the gut, its nervous and immune systems and the microbiome (10 trillion or so organisms that inhabit the bowel).
IBS may be classified by the predominant stool type according to the Rome IV criteria into the following sub-types, however these are no longer considered distinct disorders, but exist on a spectrum depending on the person’s quantity, intensity, and severity of different symptoms:
- Diarrhoea predominant (IBS-D), which is the commonest sub-type.
- Constipation predominant (IBS-C).
- Mixed, fluctuating between diarrhoea and constipation (IBS-M).
- Unclassified (IBS-U).
So where does this leave the patient? She certainly has a history of significant gut infection and we know that this can lead to disturbances in the sensitivity and motility of the gut, but these were not manifest prior to her holiday.
A careful review of her diet and lifestyle should be undertaken. The question ‘What did you eat yesterday?’ is often revealing. Young people, particularly those who have just started university, may develop less healthy dietary habits; for example, eating more takeaways and drinking more alcohol. They may be sleeping less because of increased time spent studying or socialising, and because physical activity levels may drop. Together with exam stress, this is enough to disrupt the interaction between brain, bowel and biome.
Behaviour change is hard and needs support, although the NICE guidance2 suggests the importance of self-management should be emphasised to people with IBS.
In terms of diet, people with the condition should eat regular meals, not skip meals, take time over eating and avoid excess caffeine, nicotine, alcohol and fizzy or diet drinks. In addition, complex indigestible carbohydrates, often found in ready meals and starchy foods, should be avoided or consumed in moderation. Excess fat or spicy foods may also trigger symptoms, as may some fruit, so NICE guidance recommends not eating more than three portions a day.
Specific exclusion diets such as low FODMAP, wheat or dairy-free diets should only be undertaken when the basics are right and with the support of an appropriately trained healthcare professional. This is because they are difficult to execute well. The low FODMAP diet requires the structured reintroduction of foods to identify triggers and to make sure people don’t become deplete in essential nutrients.
Lifestyle is also important. Appropriate amounts of sleep, relaxation and exercise are key to normal bowel function. If stress is a factor, it may be worth exploring the key triggers (in this case, exams), and strategies to manage these. A range of psychological approaches has been shown to be effective. Such interventions may include brief interventions in behaviour change, cognitive behaviour change particularly for fears of urgency and incontinence, and web-based and multimodality interventions to address anxiety and stress. Hypnotherapy appears at least as effective as many pharmacological alternatives.
Drugs in IBS should be used for specific symptoms. Even the best drugs, for specific symptoms, are only effective in one in four people. There is a growing body of evidence for the use of probiotics. Again, these are not universally effective. If tried, they should, provided they do not cause side-effects, be given for at least two weeks before any benefit can be expected. If one strain of probiotic doesn’t work, another might. The effects are likely to be strain specific, like the effects of specific drugs.
Dr Simon Smale is a consultant gastroenterologist at the Manchester University Hospital NHS Foundation Trust and a medical adviser to the IBS Network