An upper gastrointestinal (UGI) series is a multi-step test a doctor uses to examine the upper portion of a person's gastrointestinal tract.

The person being tested swallows a chalky-tasting "milk shake" of barium and water (barium contrast material) followed by gas-producing crystals. The doctor then tracks the progress of the barium through the throat (esophagus), stomach, and the first part of the small intestine (duodenum) using a device called a fluoroscope that takes pictures. The fluoroscope is connected to a TV monitor. Several X-ray pictures are usually taken at different times and from different angles.

An upper GI series may be done to:

• Help find the cause of certain gastrointestinal symptoms, such as trouble swallowing, vomiting, or a burning or gnawing pain in the centre of the stomach.
• Detect narrow places in the upper portion of the intestinal tract (strictures), ulcers, tumours, or polyps.
• Look for problems with the squeezing motion that moves food through the intestines (motility disorders), inflamed areas of the intestine, or other problems digesting food (malabsorption syndromes). Additional tests may be needed to examine the entire intestinal tract.
• Evaluate the possible cause of regurgitating food or having trouble swallowing, which can be caused by a hiatal hernia.