Single contrast upper GI technique is a method of imaging the esophagus, stomach, and duodenum with fluoroscopy. "Single contrast" refers to imaging with barium or water-soluble contrast only, without the addition of effervescent granules.
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Indications
The single contrast upper GI study may be preferred over a double contrast technique when
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the patient is unable to turn quickly/effectively
double contrast technique requires rapid changes in patient position
evaluation for postoperative leak after surgery
large patient body habitus which would render double contrast technique suboptimal
there has been restrictive gastric surgery or there is potential obstruction and distention of the stomach or duodenum would potentially cause a great deal of pain
when you plan on performing a small bowel follow-through afterwards
Contraindications
There are few contraindications. If the patient is aspirating then a very careful and limited study could be performed with barium if necessary, otherwise consider deferring the exam. If evaluation of the esophageal or gastric mucosa is what is clinically desired, then a double contrast upper GI technique is preferred.
Water-soluble contrast should be used when evaluating for postoperative leak.
Procedure
Pre-procedure
The patient should be nil-by-mouth before the study to allow the upper gastrointestinal tract to clear. Medications with sips of water should be allowed.
Before the exam, briefly interview the patient to see what their symptoms are, how long they have been going on, if they have a history of gastro-esophageal reflux, if they have a history of upper abdominal surgery, or if they take NSAIDs chronically.
Equipment
fluoroscopic equipment
some method of compression (e.g. radiolucent paddle or leaded glove)
a 13 mm radiopaque pill taped to a tongue depressor or some other object of known size that can be used as a measurement device
One of the most important considerations for a single contrast upper GI is the density of the barium or water-soluble contrast. Contrast must be dense enough to see filling defects, but not so dense that the fluoroscopic tube "burns out" the image obscuring small (and sometimes large) lesions.
Optimal density depends on the fluoroscopic equipment and available contrast solutions. In general, 40% w/v is a common density target for Barium or water-soluble iodine based contrast (e.g. Gastrografin). Barium often comes in 100% w/v solutions, so a way to get to 40% w/v density is:
800 mL of 100% w/v barium added to 1200 mL of water (2000 mL total)
Glucagon/Buscopan is usually not necessary for single contrast studies.
Technique
The following technique is one possible set of images for a single contrast exam. If the exam is for postoperative leak or for evaluation of a known lesion, it can be modified.
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scout views
AP chest
AP upper abdomen
if for postoperative leak, sometimes a magnified image of the area of surgery / sutures can be helpful
The first set of images are those of an oesophagram / barium swallow but the technique is interrupted so that the stomach is not overfilled.
If the exam is for esophageal symptoms / globus sensation, then consider starting with lateral rapid sequence / cine images of the pharynx.
Then stand the patient upright in the left posterior oblique (LPO) position, hand them a cup of barium to hold with the left hand.
LPO rapid sequence of the mid and distal esophagus (with proximal esophagus if possible)
Right posterior oblique (RPO) if desired to evaluate a potential problem area
Then tilt the table into the horizontal position
put the patient in the right anterior oblique (RAO) position and get spot compression images of the duodenum
prone position: compression spot images of the gastric antrum (not for postoperative patients or patients who have a large body habitus.
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RAO: large field of view cine images of the esophagus to evaluate esophageal motility
single swallow per cine series
RAO: continuous drinking with magnified spot images of the esophageal barium column
right lateral: image(s) of the gastric fundus
RPO: image(s) of the upper gastric body and lesser curvature
supine: image(s) of the distal stomach
LPO: image(s) of the gastric antrum
LPO: image(s) of the duodenal bulb
Compression images can be mixed in with these or one can wait until bringing the patient back upright for compression views.
Then tilt the table in the vertical position (patient standing)
frontal view: lesser curvature
(optional): LPO for antrum and duodenal bulb, RPO for duodenal bulb in profile
In at least one image, get the transverse duodenum with contrast at the duodenojejunal junction.
If planning a small bowel follow through, get images of the jejunum at the end of the upper GI portion of the exam.
If the exam is to evaluate post-surgical situations (such as a Roux-en-Y bypass) then the previous set of images should be modified.
Post-procedure care
The patient should be encouraged to stay hydrated and, if using barium, not to be alarmed if white material comes out in future stools.