Radiographic Positioning of the Small Intestine

Radiographic Positioning of the Small Intestine


In this presentation, we’ll be going over
radiographic positioning and procedural considerations for the small intestine. We primarily use barium or other opaque contrast
administered one of three ways to evaluate the small intestine: Orally (most common) Reflux filling via large-volume barium enema Direct injection via a tube placed into the
small bowel, termed enteroclysis Patient preparation includes a soft or low-residue
diet for 2 days prior to study, and all food and fluid withheld after the evening meal
on the day before the examination. Breakfast is also withheld on the day of the
exam, and a cleansing enema for the colon may also be administered. For the oral method of examination, it is
termed “small bowel series” because several identical images are produced at timed intervals. Each image should be identified with a time
marker indicating the interval since the ingestion of barium. Images are obtained with the patient in either
supine or prone position. Supine images take advantages of superior
and lateral shift of the stomach, which improves the visualization of the duodenum and jejunum. Prone is used to compress the abdomen and
increase image quality (compression means less thickness of patient anatomy, therefore
less scatter radiation produced). The first image is generally taken 15 minutes
after ingestion of barium, and then again between 15 and 30 minutes. The radiologist should inspect each image
as the procedure varies according to the radiologist’s preference. Once barium reaches the ileocecal region,
fluoroscopy is used to obtain compression radiographs, which evaluate structure and
function of emptying. The examination is complete when barium is
seen in the cecum, which takes an average of 2 hours after ingestion, but can vary with
patient motility. As mentioned previously, these views can be
taken AP or PA with the MSP centered. The initial image may include the stomach
depending on radiologist preference, but generally the centering would be identical to a KUB. Center at the MSP at the level of L2 or the
iliac crest. A 14 x 17 field should be utilized, and the
exposure should be made at the end of expiration. Here you can see the difference in 15-minute
increments how the barium slowly fills the small intestine. You can also see on the 30-minute film that
barium has already entered the large intestine as we see it beginning to fill the ascending
colon. At this point, the radiologist should be consulted
to determine if spot films should be performed to visualize the terminal ileum. Here we can see the entire large intestine
has been filled with barium through to the rectum. The images on the right are spot-films taken
by the radiologist to document appropriate spilling of contrast through the ileocecal
valve and into the cecum.

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