Week 209 - Constipation/IBS

Question 1

Week 209 - Constipation/IBS: How much water on average does the colon absorb?

Answer 1

Converts 2l into 200ml

Question 2

Week 209 - Constipation/IBS: The colon can be divided into two main parts, the proximal and distal, what is the function of each?

Answer 2

• Proximal - absorbs fluids/electrolytes, bacterial fermentation.
• Distal - reservoir.

Question 3

Week 209 - Constipation/IBS: What is the normal colonic transit time?

Answer 3

25-40hrs.

Question 4

Week 209 - Constipation/IBS: What are the two types of motility that occur in the proximal colon?

Answer 4

• Non-propulsive segmentation - generated by slow-wave activity which produces circular muscle contraction - mixing/absorption of contents.
• Mass peristalsis - (1-3x/day) simultaneous smooth muscle contraction propels contents.

Question 5

Week 209 - Constipation/IBS: What are the three controlling factors of colonic motility?

Answer 5

• Intramural plexi - directly controls contractile behaviour.
• Extramural - modulate function.
• Transmitters - Stimulatory - Acetycholine and substance P. Inhibitory - VIP and Nitric Oxide.

Question 6

Week 209 - Constipation/IBS: What is the definition of constipation?

Answer 6

• Infrequent passage of small amount of faecaes, leading to symptoms.
• Is not the same as obstructed defaecation.

Question 7

Week 209 - Constipation/IBS: What are the main two mechanisms for constipation?

Answer 7

• Luminal residue insufficiency.

* Abnormalities of neuromuscular activity.

Question 8

Week 209 - Constipation/IBS: What are the causes of chronic constipation?

Answer 8

• Diet
• Purgative abuse
• Idiopathic bowel disease (IBS, slow transit, mega-colon)
• Metabolic (Hypothyroidism, hypercalcaemia, hypokalaemia, uraemia)
• Drugs (opiates, iron, ganglion-blockers, anticholinergics)
• Neuromuscular disease
• Psychiatric

Question 9

Week 209 - Constipation/IBS: Which nerve supplies the external anal sphincter?

Answer 9

Pudendal nerve

Question 10

Week 209 - Constipation/IBS: What occurs to allow defaecation?

Answer 10

• Cortical perception of rectal filling.
• Voluntary decision
• Straining
• Decreased tone in pelvic floor and sphincters.
• Anorectal angle is reduced.
• Increase in abdominal tone.
• Passage of stool.

Question 11

Week 209 - Constipation/IBS: What are the five factors that help to ensure continence?

Answer 11

• Central control.
• Functioning reservoir.
• Strong pelvic floor.
• Intact sphincter mechanism.
• Absence of peripheral neuropathy.

Question 12

Week 209 - Constipation/IBS: What are the causes of incontinence?

Answer 12

• Neonatal
• Cerebral - Old age, psychiatrically disturbed.
• Degenerative - Autonomic neuropathy, Wasting diseases.
• Trauma - Obstetric, surgical, accidents.
• Idiopathic
• Diseases

Question 13

Week 209 - Constipation/IBS: What are the four causes of obstructed defaecation?

Answer 13

• Rectocoele
• Rectal intussusception
• Anismus
• Idiopathic megarectum

Question 14

Week 209 - Constipation/IBS: What is a rectocoele?

Answer 14

Protrusion of anterior wall of rectum, commonly follows childbirth.
Herniation may lead to obstructed defaecation.

Question 15

Week 209 - Constipation/IBS: What is rectal intussusception?

Answer 15

• Preliminary stage to rectal prolapse.
• Rectal fullness or pressure.
• Tenesmus.
• Perineal pain.

Question 16

Week 209 - Constipation/IBS: What are the symptoms of obstructed defaecation syndrome?

Answer 16

• Straining
• Laxative/enema dependancy
• Incomplete evacuation
• Fragmented defaecation
• Rectal Pain
• Perineal support

Question 17

Week 209 - Constipation/IBS: What is the initial investigation for a patient presenting with chronic constipation? What are the possible findings?

Answer 17

Barium enema/colonoscopy
• Excludes carcinoma.
• Normal calibre colon/rectum.
• Megacolon/rectum

Question 18

Week 209 - Constipation/IBS: Following a barium enema for the investigation of chronic constipation, you find that the colon/rectum is of normal calibre. What are the follow-up investigations?

Answer 18

• Defaecating proctogram.
• Colonic transit study.
• Anorectal physiology.
• Endoanal ultrasound.

Question 19

Week 209 - Constipation/IBS: What are the techniques used for anorectal physiology analysis?

Answer 19

• Manometry
• Balloon inflation.
• Pudendal nerve terminal motor latency.
• EMG recording.

Question 20

Week 209 - Constipation/IBS: What is functional constipation?

Answer 20

This is chronic constipation without a known cause, also known as primary and idiopathic constipation.

Question 21

Week 209 - Constipation/IBS: What is secondary constipation?

Answer 21

Constipation caused by a drug or medical condition, also known as organic constipation.

Question 22

Week 209 - Constipation/IBS: What is the difference between chronic constipation and IBS-constipation dominant?

Answer 22

IBS-C, has more pain associated with it. Patients with less pain are classified as chronic constipation.

Question 23

Week 209 - Constipation/IBS: What is the diagnostic criteria for IBS?

Answer 23

At least 12 weeks of the last 12 months with abdo. pain/discomfort and two of the following symptoms;

• Relieved with defaecation.
• And/or change in stool frequency.
• And/or change in stool form.

Question 24

Week 209 - Constipation/IBS: What are the four types of laxatives?

Answer 24

• Bulk-forming laxatives.
• Osmotic laxatives.
• Stimulant laxatives.
• Surface-wetting laxatives.

Question 25

Week 209 - Constipation/IBS: How do bulk-forming laxatives work? Give examples.

Answer 25

* Retain fluid within the stool, increasing faecal mass, stimulate peristalsis. * Ispaghula husk, Methylcellulose.

Question 26

Week 209 - Constipation/IBS: How do osmotic laxatives work? Give examples.

Answer 26

* Increase fluid in large bowel, causing secretion and stimulation of peristalsis. * Macrogols, lactulose.

Question 27

Week 209 - Constipation/IBS: How do stimulant laxatives work? Give examples.

Answer 27

* Peristalsis by stimulating colonic nerves (Senna) | * Or by stimulating colonic and rectal nerves (bisacodyl, sodiumpicosulfate).

Question 28

Week 209 - Constipation/IBS: How do surface-wetting laxatives work? Give examples.

Answer 28

* Reduce the surface tension of the stools allowing water to enter. * Docusate, poloxamer.

Question 29

Week 209 - Constipation/IBS: How should short duration constipation be managed in adults?

Answer 29

* Adjust any constipation-inducing medication. * Dietary advice (Fluids, fibre) * And oral laxatives if these are ineffective, beginning with a bulk-forming laxative.

Question 30

Week 209 - Constipation/IBS: Aside from laxatives, what other medications should be offered for the treatment of Constipation predominant IBS?

Answer 30

* Pain management. * Antidepressants. * Probiotics.

Question 31

Week 209 - Constipation/IBS: What pain management medication should be offered to those suffering from constipation predominant IBS?

Answer 31

``` Anti-spasmodics. - Anti-cholinergic agents. - Anti-muscarinics. - Peppermint oil Anti-depressants (They have anti-cholinergic properties) ```

Question 32

Week 209 - Constipation/IBS: What is the dietary management of constipation predominant IBS?

Answer 32

* at least 1.5l water /day. | * Avoid too many carbohydrates and alcohol sugars, these can exacerbate symptoms.

Question 33

Week 209 - Constipation/IBS: What are the surgical options for dysmotility?

Answer 33

* Colectomy and ileorectal anastomosis. * Sacral nerve stimulation. * Antegrade colonic enema.

Question 34

Week 209 - Constipation/IBS: What are the surgical indications for the treatment of obstructed defecation syndrome?

Answer 34

* Rectocoele * Internal intussception * prolapse