S8) Colon and Inflammatory Bowel Disease Flashcards
Compare and contrast UC and CD in terms of:
- Location
- Pathology
- Rectum involvement
- Mucosal inflammation
- Fistula formation
What sort of epithelium is found in the large intestine?
Columnar epithelium
State three functions of the large intestine
- Removes water from all the indigestible gut contents
- Vitamin production
- Temporary storage until defaecation
Distinguish between the small intestine and the large intestine in terms of structure
- Colon is much shorter (6 feet)
- Colon is much wider (average 6cm)
- Colon has crypts not villi
Describe the structure of the wall of the colon
External longitudinal muscle is incomplete:
- Three distinct bands (teniae coli)
- Haustra are sacculations caused by contraction of teniae coli
Describe mechanism of water absorption in the colon
- H2O absorption is facilitated by ENaC
- Induced by aldosterone
- most absorption is in proximal colon
- tighter tight junctions for a bigger gradient to form and less back diffusion of ions
What is inflammatory bowel disease?
Inflammatory bowel disease is a group of clinical conditions which are characterised by the idiopathic inflammation of the GI tact and affect the overall function of the gut
What are the two common types of IBD?
- Crohn’s disease (15-30 yr olds & 60 yr olds)
- Ulcerative colitis (young adults)
Identify and describe 4 extra-intestinal problems of IBD
- MSK pain — arthritis
- Skin problems — erythema nodosum (red lumps on leg) / pyoderma gangrenosum (large painful ulcers)/ psoriasis
- Liver/biliary tree issues — Primary Sclerosing Cholangitis (PSC)
- Eye problems
Identify and describe 3 possible causes of IBD
- Genetic (1st degree relative – increased risk)
- Gut organisms (altered interaction)
- Immune response (unknown trigger – antibiotics, infections, smoking, diet)
How does Crohn’s disease present?
- Tender mass (RLQ)
- Mild perianal inflammation/ulceration
- Low grade fever
- Mildly anaemic
terminal ileum is most commonly effected so lower right quadrant pain is common
Identify 6 gross pathological features of Crohn’s disease
- Hyperaemia (build up blood in the blood vessels supplying an organ)
- Cobblestone Appearance → liner ulcers and criss cross inflamed mucosa
- Discrete superficial ulcers & deep ulcers
- Fistulae (bowel – bowel, bladder, vagina, skin) abnormal connection between two epithelial lined organs
- Mucosal Oedema
- Transmural inflammation
What are the effects of transmural inflammation as observed in CD?
- Thickening of bowel wall
- Narrowing of lumen
Identify a microscopic pathological feature of Crohn’s disease
Granuloma formation (pathognomonic)
Identify 3 investigations commonly used for CD
- Bloods (anaemia)
- CT /MRI scans (bowel wall thickening & obstruction)
- Colonoscopy (Fistulas, cobblestone appearance strictures)
hepatic flexure appears lighter due to narrowing due to crohns
How does Ulcerative colitis present?
- Mildly tender abdomen
- No perianal disease
- Normal temperature
- no localised pain as it is continuous
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Identify 6 gross pathological features of UC
- Chronic inflammatory infiltrate of lamina propria
- Crypt abscesses - more common in UC that Crohns
- Crypt distortion
- Goblet cells
- Pseudopolyps
- Loss of haustra
Identify 5 investigations commonly used for UC
- Bloods (anaemia, serum markers)
- Stool cultures
- Plain abdominal radiographs
- CT/MRI (only for uncomplicated UC)
- Colonoscopy
What is indeterminate colitis?
Indeterminate colitis refers to the 10% of cases of inflammatory bowel disease where there is difficulty distinguishing between ulcerative colitis and Crohn’s disease
Describe the three steps in the medical treatment of inflammatory bowel disease
- Aminosalicylates — sulfasalazine for flares and remission
- Corticosteroids — prednisolone for flares only
- Immunomodulators — azathioprine for fistulas / maintenance of remission
Crohn’s Disease is not curative and surgically, as little bowel must be removed as possible.
In which circumstances is this performed?
- Strictures form
- Fistulas form
Ulcerative colitis is curable surgically through a colectomy.
In which circumstances is this performed?
- Inflammation not settling
- Precancerous changes
- Toxic megacolon
describe the location if each section of the colon in the peritoneum
- upper ⅓: intra peritoneal
- middle ⅓: retroperitoneal
- lower ⅓: no peritoneum
- ascending and descending are both retroperitoneal (during development they have mesenteries but lose them)
- Transverse and sigmoid colon both have their own mesenteries
describe the pathophysiology of crohns disease
- can effect anywhere in the GI tract from mouth to anus
- ileum mainly involved
- transmural - the disease goes through the wall of the mucosa so inside and outside lumen
- skip lesions - non effected areas between effected areas
