Week 209 - IBS Flashcards
What symptoms should provoke a thorough investigation?
The Rome III criteria along associated with: rectal bleeding, weight loss, nocturnal pain, fever and a clinical suspicion of organic diarrhoea
What does the Rome III state in the disgnosis of IBS?
Must experience 2 of the following 3 criteria to be disgnosed and or experience at least 3 days a month for 3 months recurrent abdo pain:
- Improvement on defecation
- Onset assoc with change in frequency of stool
- Onset assoc with change in form of stool
What are the 3 principle subtypes of IBS?
1) IBS with constipation (>25% hard stools, 25 loose/watery),
2) IBS with diarrhoea (>25% loose/watery, <25% hard)
3) mixed IBS
What do raised stool calprotectin and / or lactoferrin imply?
Inflammation, which could be due to IBD rather than IBS and needs further investigation
What condition might lactose, Senna and Magnesium hydroxide be used to treat?
Chronic constipation
What are the principle functions of the large bowel?
> modification, storage and evac of waste prods of digestion and metabolism
extraction of water and electrolytes from fluid ileal contents
maintenance of bacterial flora and absorption of nutrients derived from bacterial degradation of luminal contents
absorbs short-chain fatty acids formed by catabolism of carbs in SB
What is Hirchsprung’s Disease?
Where a section of large bowel is permanently contracted/narrowed causing a blockage for stools. Often effects sigmoid colon and rectum. Usually diagnosed soon after birth when meconium not passed - surgically treated
Where is the myenteric plexus if the large bowel located, which parts of the NS are incorporated and what motor action does it provide to the colon?
Between the longitudinal and circular muscle of the bowel wall. Sympathetic and parasympathetic nervous systems. Motor function to longitudinal and circle muscle and secretomotor action to mucosa of colon
Where is the submucous plexus locate in the colon, what part of the NS is involved with it and what does it innervate?
Between the circular muscle and the muscularis mucosae. Only parasympathetic. Motor innervation to muscularis mucosae and mucosal receptors
What is normal colonic transit time?
25-40hrs
What types of motility occur in the proximal and distal colon?
Proximal - non-propulsive segmentation (slow wave activity of circular muscle contraction) and mass peristalsis 1-3x a day (simultaneous submucosal contraction over large area) main form of propulsive motility
Distal - primarily non-propulsive
What neurotransmitters are stimulatory in the colon?
Acetylcholine and Substance P
What neurotransmitters are inhibitory in the colon?
Vasoactive intestinal polypeptide (VIP) and Nitric Oxide
Both are vasodilators
Hoe does acetylcholine enhance colonic contractions?
It increases the duration of the regular slow waves in circular muscle (which precede expulsion of faeces)
Define constipation
Infrequent passage of small amounts of faeces leading to symptoms
What are the two main mechanisms for constipation?
1) insufficient luminal residue
2) abnormalities of neuromuscular activity (congen or acquired)
Give some causes of chronic constipation
Poor diet, purgative abuse, idiopathic e.g. IBS, metabolic (hypothyroidism, hypercalcaemia), drugs (opiates, iron, anticholinergics), neuromuscular disease (spinal cord lesions, Hirchsprung’s), psychiatric
What does the technique of manometry do and how?
It measures/assesses anorectal contractility and presence of the rectosphincteric reflex - a balloon is inflated to distend the rectum and a pressure sensor at the internal anal sphincter
Can be used to diagnose Hirchsprung’s Disease in which there is an absence of this reflex
Describe the rectosphincteric reflex
As rectal pressure increases the internal anal sphincter tone should decrease to allow of defaecation
What is needle EMG (electromyography)
A technique used in the evaluation of sacral neurological function. The pudendal nerve, innervating the external anal sphincter is a good indicator of sacral neuropathic lesion
Anal endosonography (another technique useful in investigation of faecal incontinence)
Find out more about!
What is anismus?
Failure of pelvic floor muscles to relax during attempted defaecation resulting in difficulty emptying bowels
What is tenesmus?
The feeling of incomplete emptying of bowel
Want are the main causes of obstructed defaecation?
Rectocoele
Rectal intussusception (prelim phase of rectal prolapse)
Anismus
Idiopathic megarectum
