Irritable Bowel Syndrome

Question 1

What are the 2 main plexuses of the enteric nervous system?

Answer 1

Myenteric plexus
Submucosal plexus

Question 2

What is controlled by the myenteric plexus?

Answer 2

Motility

Question 3

What is controlled by the submucosal plexus?

Answer 3

INtestinal absoprtion and secretion

Question 4

What forms the gut-brain axis?

Answer 4

Autonomic communication between the CNS and enteric nervous system

Question 5

What is meant by a disordered gut-brain interaction?

Answer 5

A heterogenous group of disorders characterised by GI symptoms related to any combination of the following:
- Motility disturbance
- Visceral hypersensitivity
- Altered mucosal immune function
- Altered gut microbiota
- Altered CNS processes

Question 6

What is irritable bowel syndrome (IBS)?

Answer 6

This refers to a group of symptoms, including abdominal pain and discomfort, bloating, and change in bowel habit (ABC), for which no underlying cause or pathology can be identified

Question 7

What are some risk factors for IBS?

Answer 7

Female (2:1)
Family history
Mental health disorder e.g. Anxiety, Depression, Stress

Question 8

What is the usual age of diagnosis of IBS?

Answer 8

<45

Question 9

What are the 3 classes of IBS?

Answer 9

IBS-C - Constipation
IBS-D - Diarrhoea
IBS-M - Mixed

Question 10

What are some symptoms of IBS?

Answer 10

Abdominal pain, usually relief by defecation
Bloating
Change in bowel habit (Diarrhoea or Constipation)

Question 11

What causes abdominal pain in IBS?

Answer 11

Inflammatory mediators can up-regulate nociceptors in the bowel and increase sensitivity of the spinal cord, causing visceral hypersensitivity

Question 12

Why is colonoscopy not recommended in IBS?

Answer 12

It requires air being forced into the intestines, which can cause pain due to increased visceral hypersensitivity

Question 13

What are some possible triggers of IBS?

Answer 13

Bread
Fibre
Infection
Menstruation
Opiates (Narcotic bowel syndrome)
Stress
Underlying fears

Question 14

What are some less common signs that could suggest IBS?

Answer 14

Tenesmus
Mucus per rectum
Nocturia
Poor sleep

Question 15

What is tenesmus?

Answer 15

A feeling of incomplete emptying after defecation

Question 16

What is meant by nocturia?

Answer 16

Waking up to urinate

Question 17

What are some red flag signs that suggest something more serious?

Answer 17

Patients >50
Short duration of symptoms
Woken to defecate
Rectal bleeding
Anaemia
FH of colorectal cancer
Recent antibiotics

Question 18

What are the 3 main points of the Rome IV diagnostic criteria for IBS?

Answer 18

1 - Recurrent abdominal pain on average at least 1 day/week in the last 3 months

2 - Associated with:
- Defecation
- Change in stool frequency
- Change in stool form

3 - Symptoms must have started ≥6 months ago

Question 19

What are some investigations required in IBS to rule out other pathology?

Answer 19

Full blood count - Anaemia
CRP - IBD
Faecal calprotectin - IBD
Anti-TTG antibodies - Coeliac’s
Faecal haemoglobin (QFIIT) - Colorectal cancer

Question 20

What is the first line dietary management strategy in IBS?

Answer 20

Regular meal times
Don’t eat too late at night
Reduce fibre in IBS-D and increase in IBS-C
Avoid trigger foods
Limit caffeine and alcohol
Limit fruit to 3 portions per day
Ensure high fluid intake

Question 21

What is the second line dietary management strategy in IBS?

Answer 21

Follow a low FODMAP diet for 2-6 weeks and then gradually reintroduce foods to find lists and trigger foods

Question 22

What does FODMAP stand for?

Answer 22

F - Fermentable
O - Oligosaccharides - Wheat, onion, legumes
D - Disaccharides - Lactose
M - Monosaccharides - Fructose
A - And
P - Polyols - Sorbitol and mannitol in fruit

Question 23

How can FODMAP foods worsen IBS symptoms?

Answer 23

They are osmotically active and rapidly fermented, so increase water delivery into the lumen and increase gas production, therefore leading to luminal distension, causing motility changes, bloating, pain, discomfort and wind

Question 24

What are some pharmacological strategies in IBS?

Answer 24

Anti-Diarrhoeals
Anti-Spasmodics
Laxatives
Tricyclic anti-depressants
SSRIs
Probiotics

Question 25

What is the first line anti-diarrhoeal used in IBS treatment?

Answer 25

Loperamide

Question 26

What are some examples of anti-spasmodics used in IBS treatment?

Answer 26

Mebeverine
Hyoscine

Question 27

What type of laxative should be used in treatment of IBS-C?

Answer 27

Polyethylene glycol based laxatives such as laxido and movicol

Question 28

Why are bulk forming laxatives not indicated in IBS-C treatment?

Answer 28

Bulk forming laxatives are high in fibre, which can act as an IBS trigger, therefore worsening symptoms

Question 29

Why is senna not indicated for long term use in IBS-C?

Answer 29

There is a risk of tachyphylaxis in which the drug is not longer useful

Question 30

Why is lactulose not indicated for use in IBS-C?

Answer 30

It can take around 3 days to work
It is a high source of sugar, which can increase gas release from gut bacteria, worsening bloating

Question 31

What is linaclotide and how does it work?

Answer 31

This is a polyethylene glycol (PEG) based laxative, which agonises granulate cyclase, therefore increasing cGMP and thus increasing intestinal secretion and reducing abdominal pain

Question 32

What is the first line tricyclic anti-depressant used in IBS?

Answer 32

Amitriptyline

Question 33

How does amitriptyline help in the treatment of IBS?

Answer 33

It reduces afferent signals from the gut in low doses, and so decreases abdominal cramping and nocturia

Question 34

What are some non-pharmacological treatments of IBS?

Answer 34

CBT
Hypnotherapy

Question 35

For how long should probiotics be trialled in IBS?

Answer 35

4 weeks