Small bowel

Question 1

What is the blood supply to the foregut? (1st and 2nd part of the duodenum)

Answer 1

Superior pancreatoduodenal artery (arises from the coeliac trunk)

Question 2

What is the blood supply to the midgut? (3rd and 4th part of duodenum, jejunum, ileum and appendix)

Answer 2

Superior mesenteric artery

Question 3

In terms of physiology, what happens in the duodenum?

Answer 3

• Preparation for absoprtion
• Receipt of bile and pancreatic duct (through sphincter of oddi)
• Brunners gland secrete bicarbonate which neutralises stomach acid

Question 4

In terms of physiology, what happens in the jejunum?

Answer 4

Sugar, amino acids and fatty acids and absorbed

Question 5

In terms of physiology, what happens in the iluem?

Answer 5

Absorption of vitamin B12 and bile acids

Question 6

Where is vitamin B12 absorbed?

Answer 6

Ileum

Question 7

What are the signs and symptoms of a small bowel obstruction?

Answer 7

Colicky pain
Absolute constipation
Vomiting (may be faectulant depending on the location of the obstruction)
Distention

High pitched bowel sounds
Distention
Look for a potential cause!

Question 8

What can cause a small bowel obstruction?

Answer 8

1. Obstruction from within the lumen (gallstone, food, bezoar etc)
2. Obstruction within the wall (tumours, crohns disease, post radiation scars)
3. Outside the wall of the bowel (Adhesions, Herniation)
   Adhesions are the most common cause of obstruction in the devloped world.

Question 9

How does bowel ischaemia due to a strangulated hernia present?

Answer 9

Constant and severe pain in the abdomen +/- guarding.

Hernia will be tense and irreducable

Question 10

What investigations do you need to order if you suspect a patients has a small bowel obstruction?

Answer 10

Abdominal X Ray
Contrast CT
Gastrograffin study

Question 11

What would you expect to see on an abdominal X ray in a patient with a small bowel obstruction?

Answer 11

Dilated bowel with an air fluid level

Question 12

What is the treatment for a small bowel obstruction?

Answer 12

• Depends on cause. If there is strangulation, perforation or ischaemia then you need to take them to theatre early.
• “Drip and suck’ used in adhesions where patients are given fluids (NaCl with pottassium as they tend to be hypkalaemic and alkalotic especially if they have been vomiting) and an NG tube is inserted
• Catheterise
• Surgical laparotomy to find and treat the obstruction + antibiotics

Question 13

What investigations should you do if you suspect an arterial occlusion causing ischaemia of the small bowel?

Answer 13

CT angiogram

Question 14

How does chronic ischaemia of the bowel present and what causes it?

Answer 14

Crampy angina like pain on exertion.

Causes by atheroscelrosis of the SMA

Question 15

How does acute ischaemia of the bowel present and what causes it?

Answer 15

Caused by either arterial occulsion which is usually an embolus from AF

Question 16

Why is the small bowel more likely to die due to arterial occlusion that the large bowel?

Answer 16

The large bowel has the marginal artery of drummond which acts as a back up supply.

Question 17

What is a meckels diverticulum?

Answer 17

A congential diverticulum that is vestigal remnamt of the vitelline duct.

• Within 2 feet of the ileocaecal valve
• Present in approximately 2% of the population
• Most people are asymptomatic but if symptoms for appear then it is before 2 years old
• It has its own blood supply (terminal branch of the SMA) which means it can become obstructed, infected or undergo malignant changes.

Question 18

What are the symptoms of a symptomatic meckels diverticulum?

Answer 18

• Symptoms typically occur before 2 years of age
• Melaena followed by intestinal obstuctionm volvulum and intrasussecption
• Can present like appendicitis
• Rarely presents with abdominal pain and raised serum amylase levels due to ectopic pancreatic tissue

Question 19

What is the ‘rule of 2s’ that is relevant in meckels diverticulum?

Answer 19

2% of the population 
2 feet proximal to the ileocaecal valve 
2 inches in length 
2 types of ectopic tissue (gastric and pancratic)
2 years old at presentation 
2: 1 Male: female ration

Question 20

What investigation do you do to look for meckels diverticulum in children?

Answer 20

Technetium scan (looks for gastric mucosa)
Ultrasound
CT

Question 21

What is the treatment for meckels diverticulum?

Answer 21

Laprascopic resection of the meckels diverticulum

Question 22

Are asymptomatic meckels divertculum treated?

Answer 22

They are often treated during appendicetomies fi found to reduce the risk of complications occuring later.

Question 23

What are the main tumours than occur in the small bowel?

Answer 23

Primary tumours are rare but include

• T cell lymphoma (associated with coeliac disease)
• Carcinoid tumours
• Carcinomas (appearance similar to colorectal carcinoma. Associated with crohns and colecical disease and tend to present late, often with liver mets)
• Metastases come from the ovary, colon and stomach.

Question 24

What are the four main types of fistulas that can occur?

Answer 24

1. Enterocutaneous: Intestine - skin.
   - High or low output depending on the source
   - Result from rupture of an abscess cavity onto the skin
   - Skin should be protected by covering with a stoma bag
2. Enteroenteric/enterocolic
3. Enterovaginal
4. Enterovesicular

Question 25

How are fistulas managed?

Answer 25

• Conservative measures as they will heal if there is no inflammation or distal obstruction
• Protect overlying skin with a stoma bag
• Octreotide may help in high output fistulas
• TPN