Week 209 - Constipation/IBS Flashcards
Week 209 - Constipation/IBS: How much water on average does the colon absorb?
Converts 2l into 200ml
Week 209 - Constipation/IBS: The colon can be divided into two main parts, the proximal and distal, what is the function of each?
- Proximal - absorbs fluids/electrolytes, bacterial fermentation.
- Distal - reservoir.
Week 209 - Constipation/IBS: What is the normal colonic transit time?
25-40hrs.
Week 209 - Constipation/IBS: What are the two types of motility that occur in the proximal colon?
- 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.
Week 209 - Constipation/IBS: What are the three controlling factors of colonic motility?
- Intramural plexi - directly controls contractile behaviour.
- Extramural - modulate function.
- Transmitters - Stimulatory - Acetycholine and substance P. Inhibitory - VIP and Nitric Oxide.
Week 209 - Constipation/IBS: What is the definition of constipation?
- Infrequent passage of small amount of faecaes, leading to symptoms.
- Is not the same as obstructed defaecation.
Week 209 - Constipation/IBS: What are the main two mechanisms for constipation?
- Luminal residue insufficiency.
* Abnormalities of neuromuscular activity.
Week 209 - Constipation/IBS: What are the causes of chronic constipation?
- 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
Week 209 - Constipation/IBS: Which nerve supplies the external anal sphincter?
Pudendal nerve
Week 209 - Constipation/IBS: What occurs to allow defaecation?
- 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.
Week 209 - Constipation/IBS: What are the five factors that help to ensure continence?
- Central control.
- Functioning reservoir.
- Strong pelvic floor.
- Intact sphincter mechanism.
- Absence of peripheral neuropathy.
Week 209 - Constipation/IBS: What are the causes of incontinence?
- Neonatal
- Cerebral - Old age, psychiatrically disturbed.
- Degenerative - Autonomic neuropathy, Wasting diseases.
- Trauma - Obstetric, surgical, accidents.
- Idiopathic
- Diseases
Week 209 - Constipation/IBS: What are the four causes of obstructed defaecation?
- Rectocoele
- Rectal intussusception
- Anismus
- Idiopathic megarectum
Week 209 - Constipation/IBS: What is a rectocoele?
Protrusion of anterior wall of rectum, commonly follows childbirth.
Herniation may lead to obstructed defaecation.
Week 209 - Constipation/IBS: What is rectal intussusception?
- Preliminary stage to rectal prolapse.
- Rectal fullness or pressure.
- Tenesmus.
- Perineal pain.
Week 209 - Constipation/IBS: What are the symptoms of obstructed defaecation syndrome?
- Straining
- Laxative/enema dependancy
- Incomplete evacuation
- Fragmented defaecation
- Rectal Pain
- Perineal support
Week 209 - Constipation/IBS: What is the initial investigation for a patient presenting with chronic constipation? What are the possible findings?
Barium enema/colonoscopy
• Excludes carcinoma.
• Normal calibre colon/rectum.
• Megacolon/rectum
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?
- Defaecating proctogram.
- Colonic transit study.
- Anorectal physiology.
- Endoanal ultrasound.
Week 209 - Constipation/IBS: What are the techniques used for anorectal physiology analysis?
- Manometry
- Balloon inflation.
- Pudendal nerve terminal motor latency.
- EMG recording.
Week 209 - Constipation/IBS: What is functional constipation?
This is chronic constipation without a known cause, also known as primary and idiopathic constipation.
Week 209 - Constipation/IBS: What is secondary constipation?
Constipation caused by a drug or medical condition, also known as organic constipation.
Week 209 - Constipation/IBS: What is the difference between chronic constipation and IBS-constipation dominant?
IBS-C, has more pain associated with it. Patients with less pain are classified as chronic constipation.
Week 209 - Constipation/IBS: What is the diagnostic criteria for IBS?
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.
Week 209 - Constipation/IBS: What are the four types of laxatives?
- Bulk-forming laxatives.
- Osmotic laxatives.
- Stimulant laxatives.
- Surface-wetting laxatives.
