Condition Specific Radiology: Localized Ileus

OVERVIEW

This page is dedicated to covering how a localized ileus will appear on different types of radiological imaging studies.

BASIC CHARACTERISTICS

Fundamentally an ileus refers to the atony (loss of tone) of part/or all of the intestines. In the case of a localized ileus only a few bowel loops will be involved in this atonic process. This means that the bowels will be unable to contract normally and move waste out of the body. While there can be a number of different causes of ileus, the shared features of what a ileus actually is helps with radiological analysis.

The loss of contractions/muscular tone throughout the intestines will lead to bowel dilation. Whats more, waste will be unable to move effectively thought the GI tract (source)
The loss of contractions/muscular tone throughout the intestines will lead to bowel dilation. Whats more, waste will be unable to move effectively thought the GI tract (source)

Here are some features of a ileus that can be observed across all imaging studies:

  • Location: typical it is the small bowel that is involved in this process.
  • Dilated bowel loops: the normal intestine is < 2.5 cm in diameter. This diameter will often be increased in portions of the small intestine involved in the localized ileus. It is important to note that these loops do not dilate as much as ones seen in an obstructive process (like a small bowel obstruction).
SUPINE ABDOMINAL X-RAY (KUB)

An abdominal X-ray can be one of the first studies ordered when a ileus is suspected. The supine view will be one of the images collected.

 

Some key features to keep in mind for the appearance of a localized ileus on a supine KUB

  • Location: typical it is the small bowel that is involved in this process.
  • Dilated bowel loops: the normal intestine is < 2.5 cm in diameter. This diameter will often be increased in portions of the small intestine involved in the localized ileus. It is important to note that these loops do not dilate as much as ones seen in an obstructive process (like a small bowel obstruction).
  • Air/fluid levels: given that this patient’s orientation is supine, these air/fluid levels generally are not seen on this view.
  • Gas in sigmoid/rectum: often gas will be present in the sigmoid colon or rectum, because it can move past the localized ileus.
UPRIGHT ABDOMINAL X-RAY (KUB)

An abdominal X-ray can be one of the first studies ordered when a ileus is suspected. The supine view will be one of the images collected.

This upright KUB shows a focal ileus (red arrows) in a patient with pancreatitis (source)
This upright KUB shows a focal ileus (red arrows) in a patient with pancreatitis. Only a few bowel loops are involved and they are dilated (with a loss of their intestinal markings, source)

Some key features to keep in mind for the appearance of a localized ileus on a supine KUB

  • Location: typical it is the small bowel that is involved in this process.
  • Dilated bowel loops: the normal intestine is < 2.5 cm in diameter. This diameter will often be increased in portions of the small intestine involved in the localized ileus. It is important to note that these loops do not dilate as much as ones seen in an obstructive process (like a small bowel obstruction).
  • Air/fluid levels: these can be most easily seen on the upright film. They can be seen in the portions of the bowel that are involved in the localized ileus.
  • Gas in sigmoid/rectum: often gas will be present in the sigmoid colon or rectum, because it can move past the localized ileus.
COMPUTIRIZED TOMOGRAPHY (CT-SCAN)

 

MAGNETIC REASONANCE IMAGING (MRI)

 

Page Updated: 10.08.2016