Radiology of the Acute Abdomen

Question 1

What extra-abdominal conditions can cause an acute abdomen?

Answer 1

MI

Pneumonia

Question 2

What are the broad possible abdominal causes of acute abdomen?

Answer 2

Inflammation
Obstruction
Perforation
Ischaemia

Question 3

What radiological investigations can be used for an acute abdomen?

Answer 3

Plain film
Ultrasound
CT

Question 4

Describe what is meant by the silhouette sign

Answer 4

The phenomenon that tissues can be seen on imaging when that tissue is situated next to another tissue/substance of a different density

Question 5

Fat appears slightly darker than other soft tissues on plain film. T/F?

Answer 5

True

Question 6

If there is an acute abdomen and no psoas muscles can be seen on AXR, what could this indicate?

Answer 6

Burst aneurysm

Question 7

What condition is a porcelain gallbladder (seen on CT) associated with?

Answer 7

Gallbladder cancer

Question 8

What does bowel seen outside of the pelvis on AXR indicate?

Answer 8

Herniation

Question 9

Why is the gallbladder not usually visible on AXR?

Answer 9

It cannot be distinguished from the liver

Question 10

The bladder is always visible on AXR. T/F?

Answer 10

False - only if enlarged/full

Question 11

Describe how the small and large colon can be differentiated on AXR?

Answer 11

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

Question 12

Describe the appearance of gas and faeces in the colon on AXR?

Answer 12

Mottled appearance

Question 13

Why is it important to look for the presence of gas in the rectum on AXR?

Answer 13

The absence of gas in the rectum can indicate obstruction

Question 14

The transverse and sigmoid colons are mobile and can be confused on AXR. T/F?

Answer 14

True

Question 15

What is the name of the anatomical variant where the colon exists above the liver?

Answer 15

Chilaiditi’s syndrome

Question 16

What is the significance of chiladiti’s syndrome?

Answer 16

It can be confused for free has beneath the diaphragm.

Question 17

Why might gas be seen within the biliary tree on AXR?

Answer 17

Due to previous surgery or gallstone ileus

Question 18

How useful is AXR for investigating Inflammation in the abdomen?

Answer 18

It is useful for colitis but is non-specific in other inflammatory conditions

Question 19

What is the pathopneumonic sign of colitis on AXR?

Answer 19

Thumb-printing

Question 20

Why is toxic dilatation of the colon dangerous?

Answer 20

High morbidity and mortality as it can cause the colon wall to split, become ischaemic and perforate

Question 21

Describe the appearance of ‘burnt out’ colitis on AXR?

Answer 21

No haustrations and the colon loss tubular and straight. No longer active inflammation so no thumb-printing seen.

Question 22

AXR should not be requested in suspected appendicitis, but what may be seen in this case?

Answer 22

Appendicolith - a calcified deposit in the appendix

Question 23

What is meant by fat stranding?

Answer 23

Refers to water within the fat which creates a dark, streaky appearance.

Question 24

What are the different possible presentations of cholecystitis on CT?

Answer 24

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

Question 25

What imaging test should be used to investigate cholecystitis?

Answer 25

Ultrasound

Question 26

Why may CT be used in a patient with pancreatitis?

Answer 26

When there is a diagnosis of pancreatitis and the patient is deteriorating to investigate possible pancreatic ischaemia, necrosis and abscess formation.

Question 27

What type of plain film is sensitive fo free gas?

Answer 27

CXR

Question 28

Describe the appearance of penumoperitoneum on CXR?

Answer 28

Crescent of gas lucency at the hemidiaphragm or an abnormal linear gas line across the central diaphragm (which is not normally visible)

Question 29

Describe the appearance of penumoperitoneum on AXR?

Answer 29

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

Question 30

Which imaging modality can be used to look for the cause of abdominal obstruction?

Answer 30

CT

Question 31

Describe the appearance of small/large colonic obstruction on AXR?

Answer 31

Upstream to the obstruction there is distension and downstream to the obstruction there will be less or no gas in the colon

Question 32

What part of the colon will distend if there is colonic obstruction and an open ileo-caecal valve?

Answer 32

Small colon

Question 33

What part of the colon will distend if there is colonic obstruction and an closed ileo-caecal valve?

Answer 33

Caecum

Question 34

What imaging modality is the first choice to investigate possible abdominal ischaemia?

Answer 34

CT

Question 35

What late sign of ischaemia can be seen on AXR?

Answer 35

Crescents of gas superimposed over bowel

Question 36

What early signs of ischaemia can be seen on abdominal CT?

Answer 36

Bowel does not enhance properly on CT when it is ischaemic

Question 37

Other than looking at the bowel itself, what structures are important to assess on CT when investigating possible ischaemia?

Answer 37

Main blood vessels to see whether or not these are occluded.