12. Large Intestine And Inflammatory Bowel Disease

Question 1

Give an example of a vitamin produced in the large intestine

Answer 1

Vitamin K by bacteria

Question 2

What leads to the formation of sacculations in the large intestine? What are the saturation called?

Answer 2

External longitudinal muscle is incomplete, forms 3 distinct bands called teniae coli, which cause sacculations when they contract.
Sacculations are called haustra.

Question 3

What features aid water absorption in the large intestine?

Answer 3

Apical ENaC ion channels facilitate water absorption.
Na+/K+ ATPase sets up the concentration gradient.
Tight junctions between cells are smaller, so water that has been absorbed cannot escape back into the lumen of the large intestine.
ENaC channels are induced by aldosterone.

Question 4

Give 2 examples of extra-intestinal problems that can occur with an inflammatory bowel disease

Answer 4

MSK pain - arthritis.
Skin - erythema nodosum, pyoderma gangrenosum, psoriasis.
Liver/biliary tree - primary sclerosing cholangitis.
Eye problems.

Question 5

Give 2 causes of irritable bowel disease

Answer 5

Genetic - first degree relative increased risk.
Gut organisms - altered interactions.
Immune response eg triggered by smoking, infections, antibiotics, diet.

Question 6

How may a patient with Crohn’s disease present?

Answer 6

15-30 years and >60 years old.
Weight loss.
Right lower quadrant pain with palpable tender mass.
Mild perianal inflammation/ulceration.
Low grade fever.
Mildly anaemic.
Non-bloody frequent loose stools.

Question 7

What is seen pathologically in the bowel of a patient with Crohn’s disease?

Answer 7

Hyperaemia.
Mucosal oedema.
Discrete superficial ulcers.
Deeper ulcers.
Transmural inflammation.
Cobblestone appearance.
Fistulae.
Fibrosis.

Question 8

What causes the cobblestone appearance of the bowel in Crohn’s?

Answer 8

Is caused by linear ulcers criss-crossing.

Question 9

Why does Crohn’s lead to thickening of the bowel wall and narrowing of the lumen?

Answer 9

Repeated process of transmural inflammation and healing.

Question 10

What type of chronic inflammatory cells are seen in histologies of patients with Crohn’s?

Answer 10

Granulomas.

Question 11

Give 3 ways of investigating a patient for Crohn’s disease

Answer 11

Blood test - anaemia.
CT/MRI - bowel wall thickening, obstruction, extramural problems, strictures.
Barium enema/follow through - strictures/fistulae.
Colonoscopy - only of large intestine.

Question 12

How may a patient with ulcerative colitis present?

Answer 12

Young adult.
Frequent loose bloody stools with mucus.
Weight loss.
Mild lower abdominal pain/cramping with a mildly tender abdomen.

Question 13

What is seen pathologically in the bowel of a patient with ulcerative colitis?

Answer 13

Chronic inflammatory infiltrate of lamina propria (mucosa).
Crypt abscesses - crypt distortion.
Goblet cells.
Pseudopolyps.
Loss of haustra.

Question 14

Give 3 ways of investigating a patient for ulcerative colitis

Answer 14

Blood test - anaemia, serum markers.
Stool cultures.
Plain abdominal radiographs.
Barium enema - ulceration.
CT/MRI - lead pipe colon due to loss of haustra.
Colonoscopy.

Question 15

What is indeterminate colitis?

Answer 15

Name given to the condition found in 10% of patients, where disorder cannot be classified, due to containing features of both Crohn’s disease and ulcerative colitis.

Question 16

What layers of the intestine are affected in Crohn’s vs ulcerative colitis?

Answer 16

Crohn’s - all layers.

Ulcerative colitis - mucosa.

Question 17

What are skip lesions?

Answer 17

In Crohn’s where sections of affected bowel are interjected by unaffected sections.

Question 18

Give 2 ways of treating inflammatory bowel disease medically, and what is each used for?

Answer 18

Aminosalicylates - for flares and remission.
Corticosteroids - for flares.
Immunomodulators - for fistulae/maintained even of remission when resistant to two above.

Question 19

When is surgery used as a treatment for Crohn’s?

Answer 19

Last resort as not curative.
Used when fistulae/strictures.
As little bowel is removed as possible.

Question 20

When is surgery used as a treatment for ulcerative colitis?

Answer 20

Curable with a colectomy, so used if inflammation is not settling, there are precancerous changes or a toxic megacolon.

Question 21

What part of the GI tract is affected in Crohn’s disease?

Answer 21

Anywhere from mouth to anus, but usually ileum is involved.

Question 22

What part of the GI tract is affected in ulcerative colitis?

Answer 22

Usually begins in rectum and can spread to large intestine.