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Semester 3 - Gastrointestinal > 13. Large intestine and Inflammatory Bowel Disease > Flashcards

13. Large intestine and Inflammatory Bowel Disease Flashcards

1
Q

What are the functions of the large intestine?

A
  • Removes water from all the indigestible gut contents (proximal)
  • Turns chyme into a semi solid
  • Production of certain vitamins
  • Microbiome- contains lots of commensal bacteria
  • Acts as temporary storage until defaecation (distal)
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2
Q

What type of epithelium does the large intestine have?

A

Simple columnar

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3
Q

In which part of the colon is the faeces stored?

A

Transverse and descending colon

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4
Q

Where does the colonic mucosa derive fatty acids from and what are the by-products?

A

not from blood

Short chain fatty acids derived from the fermentation of dietary fibre
- The by-products of this fermentation process include CO2, methane and hydrogen gas

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5
Q

What is the relation of different parts of the colon to the peritoneum?

A
  • Ascending and descending colon are secondary retro peritoneal
  • Transverse colon has its own mesentery (transverse mesocolon)
  • Sigmoid colon has its own mesentery
  • Rectum:
  • Upper 1/3- intra-peritoneal
  • Middle 1/3 - retroperitoneal
  • Lower 1/3- no peritoneum
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6
Q

What is the arterial supply to the midgut component of the colon?

A

Superior Mesenteric Artery:

  • ilio-colic: caecum
  • right colic: ascending colon
  • middle colic: most transverse colon
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7
Q

What is the arterial supply to the hindgut component of the colon?

A

Inferior Mesenteric Artery:

  • left colic: transverse colon and descending colon
  • sigmoid: descending colon and sigmoid colon
  • superior rectal: Upper 1/3 rectum
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8
Q

At which vertebral level are the SMA and IMA given off?

A

L1 (trans-pyloric plane) and L3 respectively

- IMA given off slightly to the left

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9
Q

Which arteires supply the lower 2/3rds of the rectum?

A
  • Middle rectal artery (from internal iliac)

- Inferior rectal artery (from internal pudendal artery from internal iliac)

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10
Q

What is the venous drainage of the midgut component of the colon?

A
  • Midgut drains into superior mesenteric vein
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11
Q

What is the venous drainage of the hindgut component of the colon?

A
  • Hindgut drains into inferior mesenteric vein
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12
Q

What is the venous drainage of the rectal component of the colon?

A
  • Upper 1/3 rectum drains into superior rectal vein

- Lower 2/3 rectum drains into system circulation via middle and inferior rectal veins

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13
Q

What is the difference in length between large and small intestine?

A
  • Large intestine much shorter (6 feet vs 20 feet)

* Large intestine is much wider (average 6cm vs 3cm)

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14
Q

Describe the longitudinal muscle layer of the colon?

A

External longitudinal muscle is incomplete

• Three distinct bands (teniae coli)

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15
Q

What are haustra and what are they due to?

A

Haustra are sacculations caused by contraction of teniae coli

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16
Q

How much water is absorbed in the colon each day and what is absorption facilitated by?

A

Approx 1500 mls of water enter colon/day
• <100 mls excreted in faeces
•Facilitated by ENaC

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17
Q

where does most of the water absorption occur in the colon and why?

A

proximal colon

Much tighter tight junctions
• Allows bigger gradient to form
• Less back diffusion of ions

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18
Q

What is inflammatory bowel disease and what are 2 common examples?

A

Group of conditions characterised by idiopathic inflammation of the GI tact
- Crohn’s disease and ulcerative colitis

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19
Q

Describe the pattern in Crohn’s disease.

A
  • Affects anywhere in GI tract
  • terminal Ileum involved in most cases
  • Transmural
  • Skip lesions
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20
Q

Describe the pattern in Ulcerative colitis.

A
  • Begins in rectum
  • Can extend to involve entire colon (pancolitis)
  • Continuous pattern
  • Mucosal inflammation - not transmural
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21
Q

What are some extra-intestinal problems of Inflammatory bowel diseases?

A
  • MSK pain (up to 50%) e.g. Arthritis
  • Skin (up to 30%) e.g. Erythema nodosum /pyoderma gangrenosum /psoriasis
  • Liver/biliary tree e.g. Primary Sclerosing Cholangitis (PSC)
  • Eye problems (up to 5%)
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22
Q

What are the causes of inflammatory bowel disease?

A
  • Genetic
  • Gut organisms (altered interaction)
  • Immune response
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23
Q

What are 2 genetic correlation with inflammatory bowel disease?

A
  • 1st degree relative increased risk

* Identical twins concordance 70%

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24
Q

What are some possible triggers for immunological causes of IBD?

A

Antibiotics, Infections, Smoking, Diet

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25
What age range do Crohn's and UC typically affect?
2 peaks for each, about 20-25 and 50 | - more common in 20s
26
What are the signs and symptoms of Crohn's?
- loose, non-bloody stools - RLQ pain - some joint pains (lower limbs) - weight loss - reduced nutrient absorption - Tender mass (RLQ) - Mild perianal inflammation/ulceration - Low grade fever - Mildly anaemic
27
What is the typical patient that will present with Crohn's disease?
* 22 year old female * 6/52 hx of 5x loose stools/day * Non bloody stools * Weight loss * Right lower quadrant pain * Some joint pains (lower limbs) * Smoker
28
What is the more likely explanation for mild anaemia in Crohn's disease?
More likely due to the inflammation rather than any bleeding - anaemia of chronic inflammation (MEH)
29
What type of oedema develops in Crohns?
Mucosal oedema
30
What is the gross appearance in Crohn's?
skip lesion - Cobblestone appearance: | Inflammed mucosa with ulceration between
31
what can form in Crohn's?
* fistulas - inflammation go through transmural wall and connect with other parts of body * discrete superficial ulcers * deeper ulcers * strictures- transmural inflammation lead to fibrosis and narrowing of lumen
32
Describe the pattern in Crohn's disease.
* Affects anywhere in GI tract * terminal Ileum involved in most cases * Transmural * Skip lesions
33
Describe the pattern in Ulcerative colitis.
* Begins in rectum * Can extend to involve entire colon (pancolitis) * Continuous pattern * Mucosal inflammation - not transmural
34
What are some extra-intestinal problems of Inflammatory bowel diseases?
* MSK pain (up to 50%) e.g. Arthritis * Skin (up to 30%) e.g. Erythema nodosum /pyoderma gangrenosum /psoriasis * Liver/biliary tree e.g. Primary Sclerosing Cholangitis (PSC) * Eye problems (up to 5%)
35
What are the causes of inflammatory bowel disease?
* Genetic * Gut organisms (altered interaction) * Immune response
36
What are 2 genetic correlation with inflammatory bowel disease?
* 1st degree relative increased risk | * Identical twins concordance 70%
37
What are some possible triggers for immunological causes of IBD?
Antibiotics, Infections, Smoking, Diet
38
What age range do Crohn's and UC typically affect?
2 peaks for each, about 20-25 and 50 | - more common in 20s
39
What are the signs and symptoms of Crohn's?
- loose, non-bloody stools - RLQ pain - some joint pains (lower limbs) - weight loss - reduced nutrient absorption - Tender mass (RLQ) - Mild perianal inflammation/ulceration - Low grade fever - Mildly anaemic
40
What is the typical patient that will present with Crohn's disease?
* 22 year old female * 6/52 hx of 5x loose stools/day * Non bloody stools * Weight loss * Right lower quadrant pain * Some joint pains (lower limbs) * Smoker
41
What is the more likely explanation for mild anaemia in Crohn's disease?
More likely due to the inflammation rather than any bleeding - anaemia of chronic inflammation (MEH)
42
What type of oedema develops in Crohns?
Mucosal oedema
43
What is the gross appearance in Crohn's?
Cobblestone appearance: | Inflammed mucosa with ulceration between
44
Where can fistula form in Crohn's?
Between the bowel and: bowel, bladder, vagina, skin
45
What is pathognomonic in Crohn's disease histology (that can differentiate it from UC)?
presence of granulomas (organised collection of epithelioid macrophages)
46
How is Crohn's investigated?
- Bloods e.g. Anaemia - CT /MRI scans e.g. Bowel wall thickening, obstruction, extramural problems - Barium enema/follow through e.g. strictures/fistula
47
which gross pathological changes of Crohn's can be seen in endoscopy?
skip lesions cobblestone appearance fistula stricture
48
What are the signs and symptoms of UC?
- Loose, bloody stools, with mucus - Mild lower abdominal pain/cramping - painful red eye (ocular complications) - mild tender abdomen - no perianal disease (ulceration/fistula) - normal temp
49
What is the typical patient that will present with UC, what will they complain of?
* 25 year old female * 8/52 hx 10 x bloody stools/day * Mucus in stools * Weight loss * Mild lower abdominal pain/cramping * Painful red eye
50
How does UC affect crypts in colon and lamina propria?
``` • Crypt abscesses (neutrophilic exudate in crypts) • Crypt distortion: - Irregular shaped glands with dysplasia - Darker crowded nuclei • reduced numbers of goblet cells ``` Also get Chronic inflammatory infiltrate of lamina propria
51
Why might pseudopolyps form in UC?
Can develop after repeated episodes • Inflammation then healing • Non neoplastic • More common in UC (vs Crohn's
52
How does the colon appear on imaging in UC?
Edges may look smoother, loss of haustra (sacculations)
53
How is UC investigated?
- Bloods: Anaemia, Serum markers - Stool cultures - Colonoscopy - Plain abdominal radiographs - Barium enema (mild cases only) - CT/MRI: Less useful in diagnosing uncomplicated UC
54
What is the overlap in presentation of Crohns and UC called?
Indeterminate colitis (10% of IBD)
55
compare the following distinguishing feature of crohn's and UC: location
Crohn's - Anywhere in GI tract | UC - rectum/colon
56
compare the following distinguishing feature of crohn's and UC: rectal involvement
Crohn's - No | UC - Yes
57
compare the following distinguishing feature of crohn's and UC: gross bleeding
Crohn's - 25% | UC - Yes
58
compare the following distinguishing feature of crohn's and UC: perianal disease
Crohn's - 75% | UC - Rare
59
compare the following distinguishing feature of crohn's and UC: fistula formation
Crohn's - Yes | UC - No
60
compare the following distinguishing feature of crohn's and UC: Malnutrition
Crohn's - Potential | UC - No
61
compare the following pathological feature of crohn's and UC: transmural inflammation
Crohn's - Yes | UC - Rare
62
compare the following pathological feature of crohn's and UC: granulomas
Crohn's - upto 75% | UC - No
63
compare the following pathological feature of crohn's and UC: fibrosis
Crohn's - common | UC - No
64
compare the following pathological feature of crohn's and UC: crypt abscesses
Crohn's - rare | UC - Yes
65
compare the following endoscopic feature of crohn's and UC: | mucosal involvement
Crohn's - skip lesions | UC - continuous
66
compare the following endoscopic feature of crohn's and UC: | aphthous ulcers
Crohn's - yes | UC - rare
67
compare the following endoscopic feature of crohn's and UC: | linear ulcers
Crohn's - yes | UC - rare
68
compare the following endoscopic feature of crohn's and UC: | friable mucosa
Crohn's - rare | UC - Yes
69
compare the following endoscopic feature of crohn's and UC: | cobblestone appearance
Crohn's - yes | UC - no
70
compare the following endoscopic feature of crohn's and UC: | fistula
Crohn's - yes | UC - no
71
compare the following endoscopic feature of crohn's and UC: | narrowing
Crohn's - yes | UC - rare
72
What is the string sign of kantour?
Marked stricture seen with a barium follow through crohn's
73
what radiological feature is seen in double contrast enema of UC?
* Lead pipe colon * Continuous lesions without skipping * Whole colon * Mucosal inflammation
74
What is a lead pipe colon?
Featureless descending and sigmoid colon • Lacking haustral markings - seen with contract enema or other imaging modalities
75
What type of appearance does UC give with continuous mucosal inflammation?
Granular appearance
76
What are medical treatments for IBD?
``` Stepwise approach 1. Aminosalicylates ◦ Sulfasalazine (5-ASA preparations), ◦ For flares and remission 2. Corticosteroids ◦ Prednisolone, ◦ for flares only 3. Immunomodulators ◦ Azathioprine (inhibits purine synthesis), ◦ Fistulas/ maintenance of remission ```
77
When are surgical treatments done for Crohns?
• Not curative Done when there are strictures or fistulas • As little bowel removed as possible - reduce absorptive surface Can result in adhesions
78
When are surgical treatments done for UC?
Curable (colectomy) • Inflammation not settling • Precancerous changes • Toxic megacolon

Semester 3 - Gastrointestinal (17 decks)

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