209 Constipation and IBS Flashcards
What is primary (functional) constipation?
Dysmotility due to mechanical problem
Never learnt
What is secondary (organic) constipation?
Constipation due to obstruction
What is obstruction defaecation syndrome?
Constipation perhaps due to chronic straining producing a stretching and redundancy of the distal rectum where compensation methods have ceased and evacuation has become impaired
Name 3 causes of idiopathic constipation
IBS
Slow transit
Megacolon/megarectum
Name 2 metabolic causes of chronic constipation
3 listed
Hypothyroidism
Hypercalcaemia
Hypokalaemia
Name a neuromuscular disease which can cause chronic constipation
Hirschsprungs
How can anorectal physiology be assessed/investigated?
Manometry
Balloon inflation - i.e. rectal sensation studies
What does 5 or fewer markers remaining on day 5 (AXR) following colonic transit studies suggest?
Normal GIT transit
Why do pts with DM become constipated?
Due to chronic dysmotility and slow transit
Which CNS diseases can develop constipation?
4 listed
Parkinsons
MS
CVA
Spinal injuries
Name 4 types of drugs which can cause constipation
7 listed
Narcotics Iron supplements Non magnesium antacids Calcium channel blockers Inadequate thyroid hormone replacement Psychotropic drugs Anticholinergic drugs
What diagnostic criteria is used to diagnose IBS?
Rome II
What is the MOA of bulk forming laxatives?
Retain fluid in stool to increase faecal mass and stimulate peristalsis and soften stool
What is the MOA of osmotic laxatives?
Increase the fluid in the large bowel –> producing distension leading to stimulation of peristalsis.
Also has stool softening properties
What is the MOA of stimulant laxatives? (esp Senna)
Stimulate colonic and rectal nerves.
Senna is hydrolysed in the large bowel by bacteria into active metabolite
What is the MOA od surface-wetting agents?
Reduce the surface tension of of the stool allowing water to penetrate and soften it
What are fcyclomine and hyoscine used for in chronic constipation?
Pain management - they’re antispasmotics.
Relaxes SM but might aggravate the constipation
How may antidepressants help constipation?
Affect serotonergic signalling but have variable anticholinergic activity
When would patients taking probiotics typically see an improvement in their constipation?
Within 6 weeks
What type of drug is Lubiprostone? (treatment of constipation)
Chloride channel activator - works in the luminal side to stimulate chloride secretion and water secretion into the lumen - soften stool, increase motility and promote spontaneous bowel movement
What are the 3 surgical options for dysmotility?
- Colectomy and iliorectal anastomosis
- SNS (sacral nerve stimulation)
- ACE procedure - antegrade colonic enema
What is the important consideration when deciding about colectomy (functionally)?
Normal small bowel motility - incase of need of temporary ileostomy.
What is SNS used for?
Faecal incontinence
What causes obstructed defaecation?
Chronic straining producing stretching and redundency of the distal rectum + pelvic problems
What commonly precedes rectocoele causing obstructed defaecation?
Childbirth
What are the 3 indications for surgery to treat obstructed defaecation?
External prolapse
Rectocoele
Rectal intersusseption
Which Surgery is more suitable for older patients to treat obstructed defaecation?
- Open rectopexy
- Perineal procedure
Perineal procedure
Which imaging method is 90% sensitive for lesions >1cm?
CT colonography
Which imaging method is good for visualising the mesorectal fascia?
MRI
Which imaging technique is useful for functional imaging of tumours?
PET scan
What does adenoma in the colon look like?
Cauliflower
Where are mets usually found with colorectal cancers?
Liver and lungs
Which important structure is commonly involved in rectal cancer?
Mesorectal fascia
What is T1 stage rectal cancer?
Confined to the mucosa + muscularis mucosa must be intact
What is T2 stage rectal cancer?
Submucosa and mucosa also compromised
What is T3 stage rectal cancer?
Cancer extending beyond the muscularis mucosa
What is T4 stage rectal cancer?
Involvement of other organs/structures
What is ERUS?
Endorectal ultrasound
What are the downfalls of ERUS?
Sometimes cant pass the probe
Field of view small
Operator dependant
What is the initial treatment of constipation?
Dietary and fluid intervention
What is the daily recommended intake of fibre?
18-30g
What pharmacological intervention is the 1st line treatment after dietary and fluid intervention has been unsuccessful in the treatment of constipation?
Bulk forming laxatives
What is the secondary pharmacological treatment if bulk forming laxatives have been unsuccessful in the treatment of constipation?
Osmotic laxatives ( if the stool remains hard)
When should a stimulant laxative be prescribed?
If the stool has softened but patient still finds them difficult to pass or complains of inadequate emptying
When should the macrogol, Arachis oil enema not be used?
If the patient has a peanut allergy
When should the macrogol, phosphate enema be used with caution?
When renal impairment or HF
