Radiology of the Acute Abdomen Flashcards
What extra-abdominal conditions can cause an acute abdomen?
MI
Pneumonia
What are the broad possible abdominal causes of acute abdomen?
Inflammation
Obstruction
Perforation
Ischaemia
What radiological investigations can be used for an acute abdomen?
Plain film
Ultrasound
CT
Describe what is meant by the silhouette sign
The phenomenon that tissues can be seen on imaging when that tissue is situated next to another tissue/substance of a different density
Fat appears slightly darker than other soft tissues on plain film. T/F?
True
If there is an acute abdomen and no psoas muscles can be seen on AXR, what could this indicate?
Burst aneurysm
What condition is a porcelain gallbladder (seen on CT) associated with?
Gallbladder cancer
What does bowel seen outside of the pelvis on AXR indicate?
Herniation
Why is the gallbladder not usually visible on AXR?
It cannot be distinguished from the liver
The bladder is always visible on AXR. T/F?
False - only if enlarged/full
Describe how the small and large colon can be differentiated on AXR?
Large colon - round pockets of gas, not contiguous, gaps between the has bubbles indicate austral contractions, ascending and descending colon exist most laterally
Small colon - exists centrally within the frame of the large bowel, more contiguous, has valvular conniventes
Describe the appearance of gas and faeces in the colon on AXR?
Mottled appearance
Why is it important to look for the presence of gas in the rectum on AXR?
The absence of gas in the rectum can indicate obstruction
The transverse and sigmoid colons are mobile and can be confused on AXR. T/F?
True
What is the name of the anatomical variant where the colon exists above the liver?
Chilaiditi’s syndrome
What is the significance of chiladiti’s syndrome?
It can be confused for free has beneath the diaphragm.
Why might gas be seen within the biliary tree on AXR?
Due to previous surgery or gallstone ileus
How useful is AXR for investigating Inflammation in the abdomen?
It is useful for colitis but is non-specific in other inflammatory conditions
What is the pathopneumonic sign of colitis on AXR?
Thumb-printing
Why is toxic dilatation of the colon dangerous?
High morbidity and mortality as it can cause the colon wall to split, become ischaemic and perforate
Describe the appearance of ‘burnt out’ colitis on AXR?
No haustrations and the colon loss tubular and straight. No longer active inflammation so no thumb-printing seen.
AXR should not be requested in suspected appendicitis, but what may be seen in this case?
Appendicolith - a calcified deposit in the appendix
What is meant by fat stranding?
Refers to water within the fat which creates a dark, streaky appearance.
What are the different possible presentations of cholecystitis on CT?
Thickened gallbladder wall and gallstones
Fat stranding and ill-defined gallbladder wall
Broken down, no longer visible gallbladder wall which is likely to be ischaemic
Gas within the gallbladder wall
What imaging test should be used to investigate cholecystitis?
Ultrasound
Why may CT be used in a patient with pancreatitis?
When there is a diagnosis of pancreatitis and the patient is deteriorating to investigate possible pancreatic ischaemia, necrosis and abscess formation.
What type of plain film is sensitive fo free gas?
CXR
Describe the appearance of penumoperitoneum on CXR?
Crescent of gas lucency at the hemidiaphragm or an abnormal linear gas line across the central diaphragm (which is not normally visible)
Describe the appearance of penumoperitoneum on AXR?
Wriggler’s sign - there is gas on both sides of the bowel wall so the thickness of the wall can be easily seen, this indicates pnemoperitoneum
Which imaging modality can be used to look for the cause of abdominal obstruction?
CT
Describe the appearance of small/large colonic obstruction on AXR?
Upstream to the obstruction there is distension and downstream to the obstruction there will be less or no gas in the colon
What part of the colon will distend if there is colonic obstruction and an open ileo-caecal valve?
Small colon
What part of the colon will distend if there is colonic obstruction and an closed ileo-caecal valve?
Caecum
What imaging modality is the first choice to investigate possible abdominal ischaemia?
CT
What late sign of ischaemia can be seen on AXR?
Crescents of gas superimposed over bowel
What early signs of ischaemia can be seen on abdominal CT?
Bowel does not enhance properly on CT when it is ischaemic
Other than looking at the bowel itself, what structures are important to assess on CT when investigating possible ischaemia?
Main blood vessels to see whether or not these are occluded.
