Radiology GI Flashcards
Why are abdominal x-rays not useful?
As they use quite a lot of radiation and you would do a CT scan anyway as they are more useful.
Also, if you spot pathology, you do a CT to check what it is, so double the radiation.
What are the risks of radiation?
- Carcinoenesis
- Genetic
- Developmental risk to foetus
Why would you request an abdominal x-ray?
- Acute abdominal pain
- Small or large bowel obstruction
- Acute exacerbation of IBD
- Renal colic
- CT now first line
How do you give a standard abdominal X-ray
Lie down -supine and x-ray will shine from the top down.
What can you see on an AXR?
- Bowel gas pattern
- Soft tissue structures
- Bones
- ABC approach:
- A = Air / gas
- B = Bowel
- C = Calcification and stones
- D = Dem bones
- E = Everything else
What is the ABDO X approach to looking at abdominal x-rays?
It is a neumonic.
A = air (where it shouldn’t be)
B = Bowel (size and wall thickness)
D = Dense structures (calcifications, bones)
O = Organs and soft tissue (liver, spleen, kidneys)
X = eXternal (objects and artifacts)
When is bowel visible?
- Gas or as fluid filled
- Low density gas acts as a contrast
- Fully fluid filled NOT visible
How can you tell the difference between small and large bowel?
Small bowel:
- Central position
- Often don’t see it because of the fast transit time of fluids
- Volvulae conniventes - cross entire wall, thin.
Large bowel:
- Peripheral position
- Haustra
- Faeces and gas slow transit time
What abnormal gas patterns are important to recognise?
- Small bowel obstruction
- Large bowel obstruction
- Paralytic ileus
- Volvulus
- Toxic megacolon
How would a patient with small bowel obstruction present?
- Vomiting (early)
- Distention (mild)
- Absolute constipation (late)
- Colicky pain
What are some causes of small bowel obstruction?
- Adhesions
- Hernia’s
- Inguinal
- Femoral
- Incisional
- Tumours
- Inflammation
How does a large bowel obstruction present?
- Vomiting (late, faeculant)
- Distention (significant)
- Pain
- Absolute constipation
What are causes of large bowel obstruction?
- Colorectal carcinoma
- Diverticular stricture
- Hernia
- Volvulus
- Pseudo-obstruction
What is a volvulus?
- Twisting around mesentry
- Enclosed bowel loop
- Dilates
- Perforation
- Ischaemia
- Dilates
- Sigmoid volvulus is more common
- Present in same way as large bowel obstruction
Describe a sigmoid volvulus
Start in LIF
Coffee bean sign towards RUQ
Dilation of proximal bowel- obstructed
Worst complication is ischamia
What features of inflammation and infection can be seen on an x-ray?
AXR not the gold standard
May see acute or chronic changes
- Mucosal thickening
- Featureless colon
- Bowel wall oedema
What is toxic megacolon?
- Acute deterioration with UC or colits
- Colonic dilation
- Oedema
- Pseudopolyps
Toxic = patient unwell
What is a lead pipe colon?
- Featureless colon
- Loss of haustra
- Ulcerative colitis
- chronic inflammation
What is thumb printing?
Oedematous thickened haustra
Thickened wall
Active inflammation - often UC
What other abnormalities can be seen on x-rays?
- Stones
- Organs /masses
- Calcification - pancreatitis, vascular, nodes
- Bones
- Artefact
- Foreign body
Why would perforation occur?
- Peptic ulcer
- Diverticular
- Tumour
- Obstruction
- Trauma
- Iatrogenic
What are contrast studies?
Used to define hollow viscera - mucosa
- Barium
- Water soluble
Common GI contrast studies:
- Swallow
- Meal
- Follow through
- Enema
Describe the pros and cons of an abdominal CT
High dose radiation
Good spatial resolution but poor contrast resolution vs MRI
Use of IV or oral / rectal contrast
What are the two different types of CT?
Low dose - Lot less radiation but reduced resolution of picture
High dose
