Irritable Bowel Syndrome

Question 1

What sort of disorder is IBS?

Answer 1

A functional disorder

Question 2

List some factors which can trigger the onset of IBS.

Answer 2

Affective disorders e.g. depression and anxiety
Psychological stress and trauma
GI infection
Antibiotic therapy
Sexual, physical or verbal abuse
Pelvic surgery
Eating disorders

Question 3

Does IBS affect more men or women? What is the ratio?

Answer 3

It affects more women in a ratio of 2:1.

Question 4

What proportion of the population has IBS?

Answer 4

10 - 20 %

Question 5

What factors can contribute to the pathophysiology of IBS?

Answer 5

Genes and the environment
Disturbed GI tract motility
Visceral hypersensitivity

Question 6

What are the mechanisms of visceral hypersensitivity?

Answer 6

Peripheral sensitisation: Inflammatory mediators up-regulate sensitivity of nociceptor terminals
Central sensitisation: Increased sensitivity of spinal neurones

Question 7

What is the evidence of hypersensitivity being a contributing factor to the pathophysiology of IBS?

Answer 7

Peripheral sensitisation: Up to 20% of IBS patients recall the onset of their symptoms after infectious gastroenteritis.
Central sensitisation: Some patients have increased pain radiation to somatic structures e.g. fibromyalgia.

Question 8

What are the Rome III criteria for the diagnosis of IBS?

Answer 8

Recurrent abdominal pain/discomfort for at least 3 days of 3 preceding months plus 2 or more of the following:

1. Improvement with defecation
2. Onset associated with change in frequency of stool
3. Onset associated with a change in form/appearance of stool

Question 9

What are the subtypes of IBS patients?

Answer 9

IBS-C (with constipation) - hard or lumpy stools >25% and loose or watery stools 25% and hard or lumpy stools 25% and loose or watery stools >25% of bowel movements.
Unsubtyped IBS (insufficient abnormality of stool consistency to meet criteria for IBS-C, D or M).

Question 10

What are pointers to the need to investigate someone’s symptoms further?

Answer 10

The presence of symptoms identified in Rome III criteria in association with rectal bleeding, nocturnal pain, fever and weight loss and a clinical suspicion of organic diarrhoea.

Question 11

What are additional symptoms to those listed in Rome III criteria that a patient may experience with IBS?

Answer 11

Bloating, urgency, sensation of incomplete emptying, mucus per rectum, nocturia (and poor sleep) and symptoms being aggravated by stress.

Question 12

What are other illnesses associated with IBS?

Answer 12

Fibromyalgia
Chronic fatigue syndrome
Temperomandibular joint dysfunction
Chronic pelvic pain
Overlap cases are likely to have more severe IBS and psychiatric problems.

Question 13

What percentage of IBS sufferers have psychological problems?

Answer 13

50% of IBS patients are depressed/anxious/hyperchonriacal.

In tertiary centres, 2/3 IBS patients have depression/anxiety

Question 14

What are alarm features in a patient’s history?

Answer 14

Age > 50
Short duration of symptoms
Woken from sleep by altered bowel habit
Rectal bleeding
Weight loss
Anaemia
FH of colorectal cancer
Recent antibiotics

Question 15

Should IBS cause rectal bleeding?

Why may patients with IBS have rectal bleeding?

Answer 15

No, it should not cause rectal bleeding, but many patients with IBS have haemorrhoids which could bleed.

Question 16

What investigations should be done?

Answer 16

FBC, ESR/plasma viscosity, CRP, antibody testing for coeliac disease (TTG), Lower GI tests if >50 or the patient has a strong family history of colorectal cancer.

Question 17

What is the treatment for IBS?

Answer 17

Dietary modification
Laxatives
Anti-motility agents
Anti-spasmodics
Anti-depressants
Stop opiate analgesics
Psychological therapy

Question 18

What anti-diarrhoeal drug is used to treat IBS?

Answer 18

Loperamide (tablets or syrup)
This is an opiate analogue.
It inhibits peristalsis and gut secretions.
Benefits diarrhoea but has no effect on pain.
Use PRN or prophylactically.

Question 19

What anti-spasmodics are used to treat IBS?

Answer 19

Mebeverine hydrochloride
Hyoscine
Dicycloverine hydrochloride
Peppermint oil

Question 20

What laxatives can be used to treat IBS?

Answer 20

PEG-based laxatives are better than lactulose, which promotes flatulence. Patients should be advised against taking lactulose.
Stimulant laxatives such as Senna are not a long term solution as the patient develops tachyphylaxis to the drugs.

Question 21

Name a 5HT4 receptor agonist that can be used to treat constipation.

Answer 21

prucalopride

Question 22

Why should opiate analgesics be stopped in IBS?

Answer 22

Prolonged use of opiates can lead to opiate/narcotic bowel syndrome.
This is characterised by:
Worsening pain control despite escalating dose
Reliance on opiates
Progression of frequency, duration and intensity of pain
No GI explanation for pain

Question 23

Why should increasing fibre intake not be used to treat constipation?

Answer 23

Fibre aggravates the pain.

Question 24

What antidepressants can be used to treat IBS symptoms?

Answer 24

Firstly, tricycyclic antidepressants such as anitriptyline.

If these are not effective, selective serotonin reuptake inhibitors (SSRIs) should be considered.

Question 25

How do tricyclic group anti-depressants such as amitriptyline help IBS symptoms?

Answer 25

Reduce diarrhoea
Reduce afferent signals from the gut (central analgesics)
Helps restore sleep pattern
Fits with “neuroplasticity” theories that there is a loss of cortical neurones in psychiatric trauma. A brain-derived neurotrophic factor which is a precursor of neurogenesis increases with treatment with the tricyclic group antidepressant.

Question 26

When should psychological therapy be used?

What should this be?

Answer 26

Psychological therapy should be used if the patient has severe anxiety/depression or if there is no response to empiric anti-depressants.
Options for therapy could be relaxation therapy, cognitive behavioural therapy, or hypnosis.

Question 27

If an increase in dietary fibre was advised, what type of fibre should this be?

Answer 27

Soluble fibre

Question 28

When should treatment with tricyclic antidepressants be considered?

Answer 28

As second line treatment if laxative, loperamide or anti-spasmodics have not helped.