•ProTip
•Air (within the body) only naturally appears in a few areas
The lungs (we breathe air in and out)
The GI tract (we swallow air and it works through the GI tract)
Hence the finding of a gastric bubble
•Air is a good landmark for certain structures
Can’t tell if something is bowel?
Does it have air in it?
(Then it’s bowel)
•Air is a good landmark for serious pathology
Air in the abdomen other than the GI tract?
This is “Free air in the abdomen”
SUPER bad: Generally means a perforation -> urgent surgery
•Cholecystitis
An inflamed gallbladder
Recall: Stones in the gallbladder not doing anything (asymptomatic) = cholelithiasis.
(Recall your anatomy). The gallbladder will always be associated with the liver.
(Recall your pathophysiology). If the gallbladder is obstructed (frequently by a stone), it will contract, but nothing will go out to the ducts (due to the obstruction). This irritates the gallbladder. It will generally be dilated (bigger), inflamed, and have surrounding edema.
ProTip: Some stones are visible in the gallbladder (helps with the diagnosis). Some stones are so tiny, they aren’t visible (think “sand”). When the gallbladder contracts, it still can’t contract much (picture a water balloon full of water and sand – it’s still fairly malleable, until it is squeezed – the sum total of sand in the gallbladder acts like a stone itself).
•Gallbladder stones / Cholelithiasis
Can sometimes be seen on US
US waves have trouble going around/through stones, so a “shadow” appears.
•Diverticulitis
Many patients will have “diverticula” – outpouchings within the colon wall (on colonoscopy they look like potholes). At baseline, they do nothing (asymptomatic; no affect on colon function). The diagnosis is diverticulosis.
Diverticula can become inflamed – this is diverticulitis (both attendings and patients will challenge you on the difference between the two). ProTip: “itis” at the end of a condition, generally indicates inflammation.
ProTip: It is not uncommon to see a small “air bubble” outside the colon in a case of acute diverticulitis. This is considered a micro-perforation. This does not generally indicate a direct need to go to the OR (many surgeons will say all diverticulitis cases have a micro-perforation).
•Hernia
A hernia is technically a hole or opening. If you find a hernia on exam, an US or CT can help further define the hernia and detail its contents.
On CT, you will see levels where bowel contents are clearly outside the natural abdominal space. If you search a little, you can find were the hernia (i.e. opening) is, and see the contents going through it.
•Inflammatory Bowel Disease (IBD)
Ulcerative colitis will show inflammation of the colon (from the anus, and more proximally as the condition becomes more extensive)
Crohn’s disease may show spotty inflammation throughout the whole of the GI tract.
Note: Imaging almost never defines the diagnosis. History, exam, lab testing, and biopsies, will be used to help finalize the diagnosis.
•GI obstruction
If there is an obstruction in the “pipe” (GI tract), contents cannot move forward.
Air and fluid are mixed/sloshed together in the GI tract (normally). If that material can’t move, it settles, and the air and fluid separate.
Eventually an “air/fluid” level develops (air rises in its section of the gut, and fluid sinks)
•Appendicitis
The appendix (normally) is a small finger-like appendage off of the cecum
Inflammation of the appendix is associated with distention of the appendix, thickening of the wall, and surrounding edema.
•Pancreatitis
The pancreas (normally) is a centralized structure in the abdomen (personally, I look for a structure that is in the middle and “points” to the (pt’s) left – that’s the tail of the pancreas)
Inflammation of the pancreas is usually identified on CT imaging
Inflammation can cause it to look “fluffier” (less well defined)
It can be associated with surrounding “fat stranding,” cyst formation, or necrosis
Imaging should fit the clinical picture (use your patient as a guide)
•Future Gastroenterologists and Radiologists
Acute pancreatitis can be detailed on CT imaging with the Balthazar Score – I’ve never seen it done in practice, please be the first!)
•Abdominal Aortic Aneurysm
Technically a vascular issue, but can be found incidentally on abdominal imaging looking for something else.
•The associated images here are from the same patient, viewed at different levels and from different directions
•Foreign Body
Can be found on GI imaging (kids eat things, adults… have various stories, some psychiatric conditions cause a compulsion to swallow objects, etc.)
•Nasogastric Tube (NGT, NG tube)
Placed in patients who cannot, or are not safely able to, swallow
Identified by a tube that comes down through the esophagus and rests in the stomach
•Gastric Tube (G-tube)
Placed in patients with esophageal pathology making nasogastric tube placement impossible or dangerous. G-tubes are placed for chronic access to the stomach (NG tubes need to be removed eventually, as the pressure they cause against the nares will eventually wear down the tissue).
Identified by a tube entering the stomach not having gone through the esophagus.
Also readily identified on the abdominal exam of your patient
