The answer
The CT shows gas in the biliary tree
A nasogastric tube is seen in the stomach and the scan has been
preformed with IV contrast and is therefore dynamic.
What the student may say
The CT scan shows that the abnormal gas shadow seen on the scout
film over the liver is in fact in the liver itself. The pattern of the
gas with branching indicates that it is in either the ducts or the blood
vessels in the liver.
Gas in the ducts of the liver would be more common than gas in the
blood vessels which would only be seen in a critically ill patient with
gas forming organisms growing in the portal vein.
Small print
Visceroptosis is a term meaning falling organs. It was a popular
diagnosis many years ago, and all sorts of pains were ascribed to organs
being droopy. Many operations were performed to correst the
situation, with little benefit.
The naso gastric (NG) tube is seen as a bright linear foreign body
in the left anterior part of the image. The tube lies between the
stomach wall and fluid posteriorly and the gas in the stomach
anteriorly. Wide bore NG tubes are used to aspirate and drain the
stomach to prevent vomiting in patients with intestinal obstruction or
ileus. Fine bore NG tubes are used to feed patient with a functioning
gut who cannot take their requirements orally due to poor appetite or
weakness.
The black appearance under the muscles in the flank is due to fat.
Note how symmetrical it is and that it is brighter than say the gas in
the stomach.
