Pediatric gastroenterology is the study and treatment children with disorders of the gastrointestinal (GI) tract. A pediatric gastroenterologist is a physician who treats diseases of the digestive organs, including the stomach, esophagus, intestines, pancreas, liver and gallbladder. This specialist treats conditions such as abdominal pain, nausea and vomiting, ulcers, diarrhea, cancer in the GI tract, and jaundice in infants, children and adolescents.