Gastroenterology is the specialty that focuses on the digestive system and its structure, functions and disorders. These may affect the esophagus, stomach, small and large intestines, pancreas, gallbladder, liver and rectum. Disor-ders that fall under gastroenterology include appendicitis, divirticulitis, gallstones, gas-troesophageal reflux disease, peptic ulcers and stomach cancer.