Pathology of the small bowel

Question 1

Describe the rough appearance of the small bowel?

Answer 1

Many folds

Microvilli - large surface area

Question 2

What is the blood supply of the small bowel?

Answer 2

Superior mesenteric artery

Question 3

What might cause ischaemic of the small bowel?

Answer 3

A blockage in the mesenteric artery

• atherosclerosis of the mesenteric artery
• thromboembolism from the heart

Non occlusive perfusion insufficiency
- shock 
- strangulation obstructing venous return (hernia, adhesion)
Drugs (cocain)
Hyper viscosity

Question 4

What might cause a thromboembolism from the heart?

Answer 4

Atrial fibrillation

Question 5

Is bowel ischaemia usually acute or chronic?

Answer 5

Usually acute

Question 6

What is the most metabolically active part of the bowel wall?

Answer 6

The mucosa - and thus is the most sensitive to effects of hypoxia

Question 7

When does most of the tissue damage occur in non occlusive ischaemic?

Answer 7

After the reperfusion

Question 8

The longer the period of hypoxia to the small bowel the….

Answer 8

Greater the depth of the damage to the bowel wall and the greater the likelihood of complications

Question 9

As the length of time of ischaemia increases describe the type of infarct you might get?

Answer 9

Mucosal infarct

Mural infarct

Transmural infarct

Question 10

Describe what might happen after a mucosal infarct?

Answer 10

If blood supply is repaired then regeneration can occur and mucosal integrity is restored

Question 11

Describe what might happen in a mural infarct?

Answer 11

If blood supply is restored, then repair and regeneration can occur you will be left with a fibrous stricture

Question 12

Describe what might happen after a transmural infarct?

Answer 12

Gangrene - death if not resected

Question 13

What are some complications of ichaemia of the small bowel?

Answer 13

Resolution
Fibrous structure, chronic ischaemia, obstruction
Gangrene, perforation, peritonitis, sepsis, death

Question 14

What is mocker’s diverticulum?

Answer 14

Result of incomplete regression of vitello-intestinal duct

usually in distal ileum

Question 15

What might Meckel’s Diverticulum cause?

Answer 15

Bleeding, perforation or diverticulitis which mimics appendicitis

usually asymptomatic, incidental finding

Question 16

Describe roughly tumours of the small bowel?

Answer 16

Primary tumours are rare 
Secondary tumours (metasteses) more common 
- ovary 
-colon 
- stomach

Question 17

Name 3 primary tumours of the small bowel?

Answer 17

Lymphomas
Carcinoid tumours
Carcinomas

Question 18

How would you treat lymphomas of the small bowel?

Answer 18

Surgery and chemotherapy

Question 19

Describe carcinoid tumours of the small bowel?

Answer 19

They are rare, commonest site is the appendix
Small, yellow, slow growing tumours
Locally invasive

Question 20

What can carcinoid tumours of the small bowel cause?

Answer 20

Intussusception, obstruction

Flushing and diarrhoea

Question 21

Describe carcinoma of the small bowel?

Answer 21

Rare, associated with Crohns and coeliac disease
Identical to colorectal carcinoma in appearance

Presents late
Metastases to lymph nodes and liver

Question 22

Describe appendicitis?

Answer 22

IT is the commonest cause of an acute abdomen

Comments in children

Question 23

What are the symptoms of appendicitis?

Answer 23

Vomiting, abdo pain, RIF tenderness and increased WCC

Question 24

What is some of the pathology of appendicitis?

Answer 24

Acute inflammation (neutrophils)
Mucosal ulceration
Serial congestion, exudate
Pus in the lumen

Question 25

What must acute inflammation involve?

Answer 25

The muscle coat

Question 26

What is the classical presentation of appendicitis?

Answer 26

Periumbilical pain moving towards RIF Guarding Rebound tenderness

Question 27

What might be some complications of appendicitis?

Answer 27

``` Peritonitis Rupture Abscess Fistula Sepsis and liver adscess ```

Question 28

Wha is coeliac disease?

Answer 28

It is a T cell mediated autoimmune disease of the small bowel in which prolamin (wheat, barley) intolerance causes villous atrophy and malasbroption.

Question 29

What is coeliac disease caused by?

Answer 29

Caused by an abnormal reaction to a constituent of wheat flour, gluten, which damages enterocytes and reduces absorbtive capacity

Question 30

What does coeliac diseases have a strong association with?

Answer 30

HLA-B8 Dermatitis herpetigormis Childhood diabetes (commoner in Irish)

Question 31

When can coeliac disease present?

Answer 31

At any stage

Question 32

What is the normal lifespan of an enterocyte?

Answer 32

About 72hrs

Question 33

What happens to the enterocytes in coeliac disease?

Answer 33

There is an increasing loss of enterocytes due to IEL mediated damage leading to a loss of villi and loss of surface area and thus absorption

Question 34

What might you expect to see down the microscope in coeliac disease?

Answer 34

A flat mucosal biopsy with total villous atrophy

Question 35

What antibodies might you see in coeliac disease\s?

Answer 35

anti-TTG anti-endomesial anti-gliadin

Question 36

What are some of the symptoms of coeliac disease?

Answer 36

Steatorrhea - due to malabsorption of fats

Question 37

What might reduced intestinal hormone production lead to in coeliac disease?

Answer 37

Reduced intestinal hormone production leads to reduced pancreatic secretion and bile flow (CCK) leading to gallstones

Question 38

What are some of the affects of malabsorption due to coeliac disease?

Answer 38

``` Loss of weight Anaemia Abdo bloating Failure to thrive Vitamin deficiencies ```

Question 39

What are some complications of coeliac disease?

Answer 39

T cell lymphomas of the GI tract (rare) Increased risk of small bowel carcinoma Gallstones Ulcerative -jejenoilleitis