Gastroenterology - IBS

Question 1

What is IBS?

Answer 1

Irritable bowel syndrome (IBS) is a common functional bowel disorder in which abdominal pain is associated with defecation or a change in bowel habit in the absence of any structural pathology.

Question 2

How common is IBS?

Answer 2

Approximately 10-15% of the general population are affected but only 10% of these consult their doctors with symtpoms. Young women are affected 2-3 times more than young men. There is a wide overlap with non ulcer dyspepsia, chronic fatigue syndrome, dysmenorrhoea and urinary frequency. Between 5-10% have a history of childhood sexual or physical abuse.

Question 3

What are the clinical features of IBS?

Answer 3

Recurrent colicky abdominal pain in the lower abdomen is relieved by defecation. Abdominal bloating worsens throughout the day; the cause is unknown but it is not excessive intestinal gas. Patients have an abnormal bowel habit. It is useful to classify these as having predominantly constipation or predominantly diarrhoea. The constipated type tends to pass infrequent pellety stools, usually with abdominal pain or proctalgia. Those with diarrhoea have frequent defecation but produce low volume stools and rarely have nocturnal symptoms. Passage of mucus is common, but rectal bleeding does not occur.

Question 4

How is IBS diagnosed?

Answer 4

NICE suggest the diagnosis of IBS should be considered if the patient has had the following for at least 6 months:

• abdominal pain, and/or
• bloating, and/or
• change in bowel habit

A positive diagnosis of IBS should be made if the patient has abdominal pain relieved by defecation or associated with altered bowel frequency stool form, in addition to 2 of the following 4 symptoms:

1) altered stool passage (straining, urgency, incomplete evacuation)
2) abdominal bloating (more common in women than men), distension, tension or hardness
3) symptoms made worse by eating
4) passage of mucus

Features such as lethargy, nausea, backache and bladder symptoms may also support the diagnosis.

Question 5

What red flag symptoms should be enquired about in a patient with suspected IBS?

Answer 5

Red flag features should be enquired about:

• rectal bleeding
• unexplained/unintentional weight loss
• family history of bowel or ovarian cancer
• onset after 60 years of age

Question 6

What investigations should be performed in IBS?

Answer 6

Investigations are normal. FBC, faecal calprotectin and sigmoidoscopy are usually done routinely, but colonoscopy should only be undertaken in older patients and those with rectal bleeding to exclude colorectal cancer and IBD. Atypical presentations require investigations to exclude organic GI disease. In diarrhoea- predominant cases, coeliac disease, lactose intolerance, thyrotoxicosis and parasitic infection should be excluded.

Question 7

How is IBS managed?

Answer 7

First-line pharmacological treatment - according to predominant symptom:

• pain: antispasmodic agents
• constipation: laxatives but avoid lactulose
• diarrhoea: loperamide is first-line

For patients with constipation who are not responding to conventional laxatives linaclotide may be considered, if:

• optimal or maximum tolerated doses of previous laxatives from different classes have not helped and
• they have had constipation for at least 12 months

Second-line pharmacological treatment
low-dose tricyclic antidepressants (e.g. amitriptyline 5-10 mg) are used in preference to selective serotonin reuptake inhibitors

Question 8

What general dietary advice should be given to patients with IBS?

Answer 8

• have regular meals and take time to eat
• avoid missing meals or leaving long gaps between eating
• drink at least 8 cups of fluid per day, especially water or - other non-caffeinated drinks such as herbal teas
• restrict tea and coffee to 3 cups per day
• reduce intake of alcohol and fizzy drinks
• consider limiting intake of high-fibre food (for example, wholemeal or high-fibre flour and breads, cereals high in bran, and whole grains such as brown rice)
• reduce intake of ‘resistant starch’ often found in processed foods
• limit fresh fruit to 3 portions per day
• for diarrhoea, avoid sorbitol
• for wind and bloating consider increasing intake of oats (for example, oat-based breakfast cereal or porridge) and linseeds (up to one tablespoon per day).