Small Bowel Pathology

Question 1

What 2 things can cause bowel ischaemia?

Answer 1

• Mesenteric arterial occlusion

- Non occlusive perfusion insufficiency

Question 2

What can occlude the superior mesenteric artery and cause bowel ischaemia?

Answer 2

1. Mesenteric artery atherosclerosis

2. Thromboembolism from heart (e.g. A.Fib)

Question 3

What NON-occlusive conditions can cause bowel ischaemia?

Answer 3

1. Shock
2. Strangulation obstructing venous return (e.g. hernia, adhesion)
3. Drugs e.g. Cocaine
4. Hyperviscosity

Question 4

Bowel ischaemia is usually ACUTE. TRUE/FALSE?

Answer 4

TRUE

- can be chronic (but this is rare)

Question 5

Describe the progression of infarction in the bowel as the blood supply gradually becomes more compromised.

Answer 5

• MUCOSAL Infarct (this will repair and regenerate as normal)
• MURAL Infarct (this will regnerate but form a fibrous stricture [like a scar])
• TRANSMURAL Infarct (this will progress to gangrene and death if this section of the bowel is not resected)

Question 6

Describe the difference in macroscopic appearance of the bowel between a Mucosal and Transmural infarct

Answer 6

Transmural Infarct is MUCH darker in colour

Mucosal = much closer to colour of normal/healthy bowel

Question 7

What is Meckel’s Diverticulum?

Answer 7

• Result of incomplete regression of vitello-intestinal duct
• Tubular structure which may contain gastric mucosa

2 inches long
2 foot above Ileocaecal (IC) valve
In 2% of people

Question 8

What does Meckel’s Diverticulum cause?

Answer 8

• bleeding
• perforation
• diverticulitis which mimics appendicitis
• BUT Commonly asymptomatic

Question 9

Primary Tumours of the small bowel are common. TRUE/FALSE?

Answer 9

FALSE

- secondary more common

Question 10

Where do secondary tumours of the small bowel metastasise from?

Answer 10

Ovary
Colon
Stomach

Question 11

What primary tumours CAN arise in the small bowel?

Answer 11

• Lymphomas
• Carcinoid tumours
• Carcinomas

Question 12

What type of Lymphoma usually develops in the small bowel?

Answer 12

ALL NON-HODGKINS:
- Maltomas (B-cell) derived (due to MALT)

• Enteropathy associated T-cell lymphomas
  (associated with Coeliac disease)

Question 13

How are lymphomas of the small bowel treated?

Answer 13

• Treated by surgery and chemotherapy

Question 14

Where do carcinoid tumours normally appear in the small bowel?

Answer 14

Commonest site is the appendix

Question 15

How do carcinoid tumours of the small bowel normally look?

Answer 15

• Small
• yellow
• slow growing
• Locally invasive

Question 16

What complications can carcinoid tumours cause?

Answer 16

• intussusception
• obstruction
• Produce hormone-like substances

Question 17

If a carcinoid tumour metastasises to the liver, what can this cause?

Answer 17

“Carcinoid syndrome”

=> Flushing and diarrhoea

Question 18

What conditions are carcinoma of the small bowel associated with?

Answer 18

Crohn’s disease and Coeliac disease

Question 19

Small bowel carcinoma is identical to colorectal carcinoma in appearance. TRUE/FALSE?

Answer 19

TRUE

Question 20

Does small bowel carcinoma tend to present early or late?

Answer 20

LATE

Question 21

Small bowel carcinomas usually metastasise to where?

Answer 21

• Lymph nodes

- Liver

Question 22

What symptoms and signs are common to appendicitis?

Answer 22

• Vomiting
• abdominal pain
• RIF tenderness
• increased WCC

Question 23

What are the potential causes of appendicitis?

Answer 23

Unknown
Faecoliths (dehydration)
Lymphoid hyperplasia
Parasites
Tumours (rare)

Question 24

Describe the pathological appearance of appendicitis?

Answer 24

• Acute inflammation (neutrophils)
• Mucosal ulceration
• Serosal congestion, exudate
• Pus in lumen
• Walls thicken
• *Acute inflammation must involve the muscle coat**

Question 25

What are the potential complications of appendicitis?

Answer 25

- Peritonitis - Rupture - Abscess - Fistula - Sepsis and liver abscess

Question 26

What is coeliac disease?

Answer 26

- abnormal reaction to a constituent of wheat flour, gluten | - this damages enterocytes and reduces absorptive capacity

Question 27

What conditions does coeliac disease have strong associations with?

Answer 27

- HLA-B8 - Dermatitis herpetiformis - childhood diabetes

Question 28

Describe how gluten causes a reaction in coeliac disease?

Answer 28

Gliadin = component of gluten that is the suspected toxic agent Mediated by T-cell lymphocytes within the small intestinal epithelium => ‘intraepithelial lymphocytes’ (IELS)

Question 29

What is the normal lifespan of an enterocyte?

Answer 29

72 hours

Question 30

Loss of enterocytes in coeliac disease leads to what consequences?

Answer 30

- loss of villous structure - loss of surface area, - reduction in absorbtion - flat duodenal mucosa

Question 31

Where is a biopsy taken in coeliac disease and why?

Answer 31

- duodenal biopsy most sensitive as proximal bowel is most affected

Question 32

What antibodies can be detected on coeliac serology?

Answer 32

- anti-TTG - anti-endomesial - anti-gliadin

Question 33

Coeliac disease causes malabsorption of what substances?

Answer 33

sugars fats amino acids water and electrolytes

Question 34

Malabsorption of fats in coeliac disease leads to what symptom?

Answer 34

steatorrhoea

Question 35

Why are patients with coeliac disease more predisposed to gallstones?

Answer 35

Reduced intestinal hormone production leads to reduced pancreatic secretion and bile flow => gallstones form

Question 36

What are the consequences of malabsorption in coeliac disease?

Answer 36

``` Loss of weight Anaemia (Fe, Vit B12, Folate) Abdominal bloating Failure to thrive Vitamin deficiencies ```

Question 37

What other consequences can arise from coeliac disease?

Answer 37

- T-cell lymphomas of GI tract - Increased risk of small bowel carcinoma - Gall stones - Ulcerative-jejenoilleitis