Irritable Bowel Syndrome Flashcards
What are the 2 main plexuses of the enteric nervous system?
Myenteric plexus
Submucosal plexus
What is controlled by the myenteric plexus?
Motility
What is controlled by the submucosal plexus?
INtestinal absoprtion and secretion
What forms the gut-brain axis?
Autonomic communication between the CNS and enteric nervous system
What is meant by a disordered gut-brain interaction?
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
What is irritable bowel syndrome (IBS)?
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
What are some risk factors for IBS?
Female (2:1)
Family history
Mental health disorder e.g. Anxiety, Depression, Stress
What is the usual age of diagnosis of IBS?
<45
What are the 3 classes of IBS?
IBS-C - Constipation
IBS-D - Diarrhoea
IBS-M - Mixed
What are some symptoms of IBS?
Abdominal pain, usually relief by defecation
Bloating
Change in bowel habit (Diarrhoea or Constipation)
What causes abdominal pain in IBS?
Inflammatory mediators can up-regulate nociceptors in the bowel and increase sensitivity of the spinal cord, causing visceral hypersensitivity
Why is colonoscopy not recommended in IBS?
It requires air being forced into the intestines, which can cause pain due to increased visceral hypersensitivity
What are some possible triggers of IBS?
Bread
Fibre
Infection
Menstruation
Opiates (Narcotic bowel syndrome)
Stress
Underlying fears
What are some less common signs that could suggest IBS?
Tenesmus
Mucus per rectum
Nocturia
Poor sleep
What is tenesmus?
A feeling of incomplete emptying after defecation
What is meant by nocturia?
Waking up to urinate
What are some red flag signs that suggest something more serious?
Patients >50
Short duration of symptoms
Woken to defecate
Rectal bleeding
Anaemia
FH of colorectal cancer
Recent antibiotics
What are the 3 main points of the Rome IV diagnostic criteria for IBS?
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
What are some investigations required in IBS to rule out other pathology?
Full blood count - Anaemia
CRP - IBD
Faecal calprotectin - IBD
Anti-TTG antibodies - Coeliac’s
Faecal haemoglobin (QFIIT) - Colorectal cancer
What is the first line dietary management strategy in IBS?
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
What is the second line dietary management strategy in IBS?
Follow a low FODMAP diet for 2-6 weeks and then gradually reintroduce foods to find lists and trigger foods
What does FODMAP stand for?
F - Fermentable
O - Oligosaccharides - Wheat, onion, legumes
D - Disaccharides - Lactose
M - Monosaccharides - Fructose
A - And
P - Polyols - Sorbitol and mannitol in fruit
How can FODMAP foods worsen IBS symptoms?
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
What are some pharmacological strategies in IBS?
Anti-Diarrhoeals
Anti-Spasmodics
Laxatives
Tricyclic anti-depressants
SSRIs
Probiotics
What is the first line anti-diarrhoeal used in IBS treatment?
Loperamide
What are some examples of anti-spasmodics used in IBS treatment?
Mebeverine
Hyoscine
What type of laxative should be used in treatment of IBS-C?
Polyethylene glycol based laxatives such as laxido and movicol
Why are bulk forming laxatives not indicated in IBS-C treatment?
Bulk forming laxatives are high in fibre, which can act as an IBS trigger, therefore worsening symptoms
Why is senna not indicated for long term use in IBS-C?
There is a risk of tachyphylaxis in which the drug is not longer useful
Why is lactulose not indicated for use in IBS-C?
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
What is linaclotide and how does it work?
This is a polyethylene glycol (PEG) based laxative, which agonises granulate cyclase, therefore increasing cGMP and thus increasing intestinal secretion and reducing abdominal pain
What is the first line tricyclic anti-depressant used in IBS?
Amitriptyline
How does amitriptyline help in the treatment of IBS?
It reduces afferent signals from the gut in low doses, and so decreases abdominal cramping and nocturia
What are some non-pharmacological treatments of IBS?
CBT
Hypnotherapy
For how long should probiotics be trialled in IBS?
4 weeks
