Gastrointestinal surgery is a treatment for diseases of the parts of the body involved in digestion. This includes the esophagus, stomach, small intestine, large intestine, and rectum. This also includes the liver, gallbladder, and pancreas. Surgery can remove a growth, whether cancerous or non-cancerous or a damaged part of the body, such as the intestines. It can also be used to repair a problem like a hernia.