|This article does not cite any references or sources. (December 2009)|
|Upper gastrointestinal series|
Upper GI series (barium swallow) of the esophagus, showing abnormalities associated with eosinophilic esophagitis.
Upper GI series, also upper gastrointestinal (GI) tract radiography, is a radiologic examination of the upper gastrointestinal tract. It consists of a series of X-ray images of the esophagus, stomach and duodenum. The most common use for this medical testing is to look for signs of ulcers, acid reflux disease, uncontrollable vomiting, or unexplained blood in the stools (hematochezia or positive fecal occult blood).
When the patient needs to undertake an upper GI, he or she is asked to take a fast on the previous day, depending on what the doctor wishes the patient to take or what might be needed for this testing. Normally, the patient must avoid solid food for up to eight hours prior to the appointment and avoid any type of consumable, including water, three hours prior to the testing.
This is a non-invasive test, consisting of an X-ray. In the X-ray room, the patient is given two medications to drink that help improve the quality of the resulting X-rays. The patient may also be administered glucagon, a pancreatic hormone that is injected intravenously. The first drink is very carbonated, made from baking-soda crystals which expands the stomach by causing gas to build in the stomach. The second drink is a contrast agent, typically a thick, chalky liquid containing a barium salt. (This test is sometimes called a barium swallow.) The barium outlines the stomach on the X-rays, helping the doctor find tumors or other abnormal areas.
The patient then has X-rays taken. The doctors usually take a series of pictures with the patient in a number of different positions to capture different poses and views of the digestive system. Normally the patient needs to hold their breath to avoid the pictures from blurring and causing unneeded challenges in diagnosing the illness.
During the test, the doctor may pump air into the stomach to make features such as small tumors easier to see.
After the test 
Patients may feel nauseated immediately after drinking the barium. This is common and may last up to 72 hours following the test. Patients may eat as normal after the procedure but it is important to drink a lot of water to allow the barium to pass through the body more easily. Constipation is common but diarrhea will affect some patients. Another common side effect is the bleaching of solid waste matter; this may last up to 48 hours.
See also 
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