A stomach doctor is called a gastroenterologist, also known as a GI doctor. Gastroenterologists are specialists with expertise in the disorders and diseases that affect the digestive system, which includes the gastrointestinal tract (esophagus, stomach, small intestine, large intestine, rectum, and anus) as well as the pancreas, liver, bile ducts, and gallbladder. They use a variety of tests to diagnose gastrointestinal (GI) diseases and conditions, including minimally invasive ways to look at the inside of your esophagus, stomach, small intestine, and large intestine. Gastroenterologists are trained to perform a number of procedures used to help diagnose and treat these conditions, such as upper endoscopy, colonoscopy, biopsy, and the various endoscopic techniques needed to visualize the digestive system, including endoscopic ultrasound. If you are experiencing any digestive issues or symptoms related to your digestive system, you should consider seeing a gastroenterologist.