Week 6 - Lower Gastrointestinal Disease

Question 1

What is the function of the large intestine and rectum?

Answer 1

• part of the digestive tract
• most digestion and absorption already done at this stage
• mainly absorbs water and electrolytes to form a solid stool

Question 2

What is acute appendicitis?

Answer 2

• sudden onset inflammation of the appendix
• acute bacterial infection of the appendix precipitated by the obstruction of the lumen (fecalith, calculus, tumour or worms) causing increased intraluminal pressure

Question 3

What are the clinical signs and symptoms of appendicitis?

Answer 3

• classically pain begins in the umbilical region of the abdomen which migrates to the right lower abdomen
• on examination there is often tenderness in the right quadrant, with involuntary guarding on palpating, due to localised peritonitis

Question 4

Visceral vs. parietal pain

Answer 4

• the sensory innervation of abdominal viscera is much less than that of other parts of the body such as skin, linings of the abdominal and thoracic cavities (parietal)
• visceral pain = referred pain - pain is felt in a different location to where the pathology is
• parietal pain = much more localised

Question 5

What is the difference between localised and generalised peritonitis?

Answer 5

• peritoneum is the lining of the abdominal cavity and the lining of the organs within the abdominal cavity
• peritonitis is inflammation of this cavity due to a variety of causes, most commonly infection
• in appendicitis the inflamed appendix on coming in contact with the abdominal wall causes localised peritonitis

Question 6

How is acute appendicitis treated?

Answer 6

Surgery and/or antibiotics

Question 7

What is pseudomembranous colitis?

Answer 7

• antibiotic associated colitis
• acute inflammation of the colon characterised by the formation of plaque like fibrinous exudate (pseudomembranes) overlying the sites of mucosal injury/parts of the large intestinal mucosa

Question 8

What is pseudomembranous colitis caused by?

Answer 8

A toxin produced by an overgrowth of C.diff, replacing the normal intestinal flora

-usually happens because the competing bowel organisms were eliminated by broad spectrum antibiotics

Question 9

What are the symptoms of pseudomembranous colitis?

Answer 9

• typically develops in patients treated with broad spectrum antibiotics
• fever and lower abdominal tenderness

Question 10

How is pseudomembranous colitis treated?

Answer 10

• discontinuation of abx
• hydration
• specifical antibacterial therapy

Question 11

What is inflammatory bowel disease?

Answer 11

-chronic inflammatory conditions of unknown aetiology affecting the GI tract

Question 12

What are the two main forms of idiopathic IBD (inflammatory bowel disease)?

Answer 12

• Crohn’s disease

- ulcerative colitis

Question 13

What is the pathogenesis of idiopathic inflammatory bowel disease?

Answer 13

• genetics
• environment
• constitutional susceptibility

Question 14

What does Crohn’s disease affect?

Answer 14

• affects from mouth to anus: particularly terminal ilium (30%), colon alone (20%), and ilium and colon (50%)
• skip lesions (not continuous) - intervening uninvolved areas
• often perianal skin involvement (75%)

Question 15

What is the pathology of Crohn’s disease?

Answer 15

• mucosal ulceration - typically fissuring
• oedema of adjacent epithelium (cobblestone)
• pseudopolyp formation regeneration
• transmural inflammation:
• active chronic inflammation with non-ceseating epithelioid granulomas
• can have fistula formation

Question 16

What are the complications of Crohn’s disease?

Answer 16

• anaemia (megaloblastic from B12 deficiency, hypo chromic microcytic from iron deficiency)
• malabsorption - fat, vitamins A, D, E, K, bile salts
• fistulas
• extra-intestinal - skin, eyes, joints (ankylosing spondylitis)
• increased risk of bowel carcinoma
• bowel obstruction and perforation

Question 17

Describe ulcerative colitis

Answer 17

• colon only
• starts in rectum - spreads proximally
• continuous disease (no skip lesions)
• mucosal disease (no transmural involvement)
• may involve whole colon, also appendix

Question 18

What are the complications of ulcerative colitis?

Answer 18

• anaemia - iron deficiency from blood loss
• electrolyte loss from diarrhoea
• extra-intestinal disease: skin, eyes, joints, bile ducts (PSC)
• increased risk of carcinoma: related to duration and severity of disease
• need for surveillance for dysplasia

Question 19

What are the mimics of IBD?

Answer 19

• ischaemic colitis
• radiation colitis
• Behçet’s disease
• pouchitis
• diversion colitis
• microscopic (lymphocytic/collagenous) colitis
• infectious colitis
• latrogenic colitis

Question 20

Name the types of neoplasia that can occur in the lower GI tract

Answer 20

• benign polyps - adenomas
• malignant adenocarcinoma (cancer)

-different stages/grades of adenocarcinoma affect prognosis and treatment

Question 21

What are the factors that could trigger colorectal carcinoma?

Answer 21

Genetic factors - (familial adenomatous polyposis, lynch syndrome (hereditary non-polyposis colorectal cancer)

Chronic inflammation - IBD - UC, Crohn’s

Dietary factors (?low fibre, ? Bile aerobes, ?rdped meat, ?lack of vitamins, antioxidants)

Question 22

What is the national bowel cancer screening (NBCSP) programme?

Answer 22

• all population 60-75 years
• faecal occult blood test (FOBT)
• if +ve - refer to colonoscopy
• look for polyps (adenomas) and carcinomas
• refer for definitive treatment

Question 23

What are the signs and symptoms of colorectal carcinoma?

Answer 23

• depends of the site of the lesion
• altered bowel habit
• blood PR
• iron deficiency anaemia
• weight loss
• disease can be advanced at the time of the presentation

Question 24

What can colorectal carcinomas be (gross)?

Answer 24

• ulcerating

- polypoid/fungating

Question 25

What is an adenoma?

Answer 25

Benign tumour of glandular epithelium

Question 26

What do almost all carcinomas arise from?

Answer 26

• benign adenomas - polyps

- the more polyps the greater the risk

Question 27

Describe the spread of colorectal carcinoma

Answer 27

• dukes stage A (above muscle layer - 5yr survival 95%)
• dukes stage B (into serosal fat, LN negative - 5 yr survival 66%)
• dukes stage C (LN involvement - 33% 5yr survival)

Question 28

Describe the T (primary tumour) part of the TNM system for colorectal carcinoma

Answer 28

Primary tumour 
Tx - not assessable 
T0 - no primary tumour 
Tis in situ - intraepithelial or intra-mucosal
T1 - submucosa 
T2 - muscularis propria 
T3 - subserosa, perirectal tissues
T4 - perforated visceral peritoneum (a) or invades other organs (b)

Question 29

Describe the N (regional lymph nodes) part of the TNM system for colorectal carcinoma

Answer 29

NX - not assessable
N0 - no LN metastases
N1 - 1-3 LN+
N2 - >4 LN+

Question 30

Describe the M (distant metastases) part of the TNM system for colorectal carcinoma

Answer 30

MX - not assessable
M0 - no distant metastases
M1 - distant metastases

Question 31

Name the parts of the lower GI tract

Answer 31

Large intestine

• ascending colon
• transverse colon
• sigmoid colon
• rectum
• anus
• appendix