6.4 Disorders of the Lower Gastrointestinal Tract

Question 1

Are there villi or microvilli in the large intestine? What about circular folds?

Answer 1

• No villi/microvilli
• No circular folds

Question 2

Outline the autoimmune mechanics of coeliac disease at a cellular level

Answer 2

• Specific MHC class II molecules that present gluten as a pathogen
• Picked up by autoreactive T cell
• Downstream immune activation and attacking of the small bowel

Question 3

GI/extraintestinal symptoms of coeliac disease

Answer 3

GIT symptoms:
- Diarrhoea, flatulence, abdo pain, bloating
- Iron deficiency anaemia/other deficiencies
- Weight loss
- Fatigue

Extraintestinal:
- Skin blistering
- Other autoimmune diseases
- Osteoporosis

Question 4

Coeliac disease Ix

Answer 4

1. Gluten challenge diet (like a shitty viral video)
2. Blood tests for antibodies
3. Endoscopy/small intestine biopsy

Question 5

Symptoms/signs of IBS

Answer 5

• Bloating
• Abdo pain
• Diarrhoea
• Constipation

Question 6

What investigations/symptoms might we check for to determine if a patient has functional bowel disease like IBS?

Answer 6

Symptoms: weight loss, rectal bleeding, perianal symptoms, mouth ulcers

Investigations: Iron studies, CBC (?anaemia), CRP, faecal calprotectin, raised platelets, low albumin

Question 7

What are the three broad characteristic principles of IBD pathogenesis?

Answer 7

• Defective host interactions with intestinal microflora (a war is being waged)
• Epithelial dysfunction (craters on the battlefield)
• Mucosal inflammatory response, driven by T cells

Question 8

Extraintestinal symptoms of IBD

Answer 8

• Anterior uveitis
• Arthritis
• Osteopenia/porosis
• Thromboembolic event

Question 9

Crohn’s Symptom

Answer 9

(Intermittent Attacks)
- Malabsorption
- Weight loss
- Perianal fissures

Question 10

What macroscopic changes can Crohn’s make to the GI tract?

Answer 10

• Transmural inflammation
• Thickened/oedematous mesentery
• Strictures
• “Cobblestoning” fibrosis and ulceration
• Skip lesions

Question 11

Crohn’s complications

Answer 11

• Bowel obstruction
• Ulcers
• Malabsorption
• Anaemia
• Carcinoma

Question 12

What is the pattern of distribution of ulcerative colitis. How deep is the ulceration?

Answer 12

• Starts in rectum
• Spreads proximally
• Inflammation is more superficial than crohn’s

Question 13

Ulcerative colitis symptoms

Answer 13

(Mostly intermittent attacks)
- Blood or pus in stool
- Diarrhoea
- Urgency

Question 14

Describe acute severe ulcerative colitis

Answer 14

• > 6 bloody bowel motions/day
• One of: elevated HR, temp, CRP, or low Hb
• This is a medical emergency

Question 15

Diverticulosis mechanism

Answer 15

• Increased intraluminal pressure from straining during defecation (due to deficiency in vegetable fibre)
• Causes mucosal “blowouts”, and circular muscle hypertrophy
• Plus, with age, tensile colonic strength decreases
• Causes diverticula to form

Question 16

Diverticulitis mechanism

Answer 16

• Inspissated (thickened) stool gets trapped in diverticula
• Causes inflammation and localised ischaemia
• Bacteria may breach mucosa

Question 17

Symptoms/investigations for acute diverticulitis

Answer 17

Symptoms: pain (usually left iliac fossa), fever, malaise, anorexia, change in bowel habirt, fever

Bloods: WCC elevated
Imaging: CT is best

Question 18

How do we manage acute diverticulitis? What if there’s no initial improvement?

Answer 18

• Nil orally
• IV fluids
• IV antibiotics
• Analgesia

If no improvement: surgery

Question 19

How does diverticular abscess differ from acute diverticulitis? How do we treat it?

Answer 19

• Walled off diverticulum
• Treated w/ IV antibiotics, radiological drainage, resection

(Smaller may go away on own; larger often need drainage and resection)

Question 20

What are the two most common types of colonic fistula formed due to diverticulosis?

Answer 20

• Colovesical
• Colovaginal

Question 21

What are some complications of diverticulitis?

Answer 21

• Fistula formation
• Bleeding
• Abscess occurrence
• Obstruction/stricture from recurrent

Question 22

What must we always exclude if we’re considering diverticulosis? How?

Answer 22

Colorectal cancer (do a colonoscopy 6 weeks after event, to let mucosa calm down and reduce rupture risk)

Question 23

Why is the appendix more likely to become gangrenous and perforate, as seen in appendicitis?

Answer 23

• End arterial supply
• More likely to become gangrenous and perforate

Question 24

Mechanistically, what is the most likely cause of appendicitis?

Answer 24

Luminal obstruction

Question 25

Why is it clinically relevant that the appendix can have multiple positions in different people?

Answer 25

Because this causes it to sit around different structures. Then, when inflamed affects those different structures to produce different symptoms.

Question 26

Why does appendicitis pain classically shift to the RIF? What structure is irritated?

Answer 26

Irritation of parietal peritoneum.

Question 27

Physical exam findings of appendicitis

Answer 27

• Tachycardia
• Fever
• RIF Tenderness

Question 28

What are some possible mechanisms for Rovsing’s sign?

Answer 28

• Pressure on peritoneum
• Shifting small intestine
• Increased pressure

Question 29

Appendicitis investigations (in a suspected case, accounting for other differentials)

Answer 29

• Bloods (raised WCC)
• Urinalysis (don’t assume UTI)
• Beta HCG in women
• Ultrasound for reproduce age females and children (radiation)
• CT scan for other people

Question 30

Appendicitis management

Answer 30

• Nil orally
• IV fluids
• Analgesia
• If not getting better, appendectomy

Question 31

What three different fates might happen to the appendix if appendicitis is not treated?

Answer 31

• Gangrene
• Suppuration
• Perforation

(GPS)