A pediatrician who specializes in the diagnosis and treatment of diseases of the digestive systems of infants, children and adolescents. This specialist treats conditions such as abdominal pain, ulcers, diarrhea, cancer and jaundice and performs complex diagnostic and therapeutic procedures using lighted scopes to see internal organs. Source: American Board of Medical Specialties, 2007. www.abms.org [7/1/2007: definition added, source added]