17) Imaging of GIT

Question 1

What types of imaging can be used for the GIT?

Answer 1

X-ray - abdominal and erect chest
Contrast studies
Ultrasound
CT/MRI
Angiography

Question 2

What types of contrast studies are there?

Answer 2

Barium swallow, enema and meal

Water soluble studies

Question 3

What imaging types are low dose radiation?

Answer 3

Ultrasound, MRI

Question 4

What imaging types are high dose radiation?

Answer 4

Barium enema, CT

Question 5

What are the risks of radiation in imaging?

Answer 5

Carcinogenesis
Genetic
Developmental risk to foetus

Question 6

Why would an abdominal X-ray be requested?

Answer 6

Acute abdominal pain (sometimes)
Small or large bowel obstruction (used as triage)
Acute exacerbation of IBD

Question 7

How is an abdominal X-ray taken?

Answer 7

Patient on back, X-ray from above

Question 8

What features can be seen on an AXR?

Answer 8

Bowel gas pattern
Soft tissue structures
Bones

Question 9

When can hollow tube be seen on X-ray?

Answer 9

If gas filled of gas and fluid filled

Slow transit time in colon and stomach so will be gas filled

Question 10

When it can be seen, what are the features of the small bowel on AXR?

Answer 10

Central position

Valvulae conniventes - lines across entire bowel lumen

Question 11

What are the features of the large bowel on AXR?

Answer 11

Peripheral position
Haustra
Faeces and gas
Transverse colon hangs down into pelvis

Question 12

What is the rule of 3/6/9 in abnormal gas patterns?

Answer 12

Small bowel obstruction if dilated >3cm
Large bowel obstruction if dilated >6cm
Caecum (if ileocaecal valve working) obstruction if dilated >9cm

Question 13

What causes small bowel obstruction?

Answer 13

Adhesions, hernias, tumours, inflammation

Question 14

How does small bowel obstruction present?

Answer 14

Vomiting (early)
Distension
Absolute constipation (late)
Colicky pain

Question 15

What causes large bowel obstruction?

Answer 15

Colorectal carcinoma (unless proven otherwise)
Diverticular stricture
Hernia
Volvulus

Question 16

How does large bowel obstruction present?

Answer 16

Distension
Pain
Absolute constipation
Vomiting (late)

Question 17

What is a volvulus?

Answer 17

Loop of intestine twisting around itself or around its mesentery

Question 18

What is the most common volvulus?

Answer 18

Sigmoid volvulus

Question 19

What can be the outcome of a volvulus?

Answer 19

Bowel loop dilates and can cut off its blood supply (in mesentery) or perforate

Question 20

What can be the treatment for a sigmoid volvulus?

Answer 20

Sigmoidoscopy - passed through twist

Question 21

What inflammation can be seen on AXR?

Answer 21

Mucosal thickening
Featureless colon (UC)
Bowel wall oedema

Question 22

Describe the features of toxic megacolon:

Answer 22

Microvascular ischaemia 
Mucosa sloughs off 
Colonic dilatation
Oedema 
Pseudopolyps

Question 23

What is thumb printing?

Answer 23

Oedematous thickened haustra due to active inflammation (UC)

Question 24

What other organs may be seen on an AXR?

Answer 24

Liver, spleen, kidneys, bladder

Question 25

What other abnormalities may be see on an AXR?

Answer 25

Stones Masses Calcification - chronic pancreatitis, vascular Foreign bodies

Question 26

What condition can a chest X-ray be used to diagnose?

Answer 26

Perforated bowel

Question 27

Why does a chest X-ray need to be used in perforated bowel?

Answer 27

To see diaphragm being elevated from viscera, with air/gas in the peritoneal cavity

Question 28

What can cause a perforated bowel?

Answer 28

``` Peptic ulcer Diverticular Tumour Obstruction Trauma ```

Question 29

When is barium contrast study used and when is water soluble contrast study used?

Answer 29

Barium if healthy | Water soluble if going into surgery

Question 30

What can a barium swallow be used for?

Answer 30

Visualise aspiration, used in elderly

Question 31

What can a barium enema be used for?

Answer 31

Injected rectally, check if anastomoses have healed in removed rectum where ileostomy has been used

Question 32

What is the L1 plane of a CT called?

Answer 32

Trans-pyloric plane

Question 33

What are the advantages of MRI scans?

Answer 33

No radiation | Good spatial and contrast resolution - differentiating between different tissues

Question 34

What can be visualised using ultrasound?

Answer 34

Gall stones Common bile duct dilation Liver, portal vein and appendix

Question 35

How is a GI angiography carried out?

Answer 35

Inject radio opaque contrast IV, then use imaging to visualise blood supply

Question 36

What can a GI angiography be used to see?

Answer 36

Bleeding | Ischaemia

Question 37

What can GI stenting be used for?

Answer 37

Removing blockages