Gastroenterology is a branch of medicine dealing with the disorders of a digestive system, esophagus, stomach, intestines, liver, pancreas, biliary tract. The most common symptoms with which patients go to a gastroenterologist are: abdominal pain, nusea and vomiting, heartburn, diarrhea, bleeding from the gastrointestinal tract. It may be common symptoms of such diseases, as stomach ulcers, duodenal ulcers, gallstones, irritable bowel syndrome and even gastrointestinal cancers or pancreatitis. Gastroenterologists order and perform gastroscopy, colonoscopy, sigmoidoscopy.