Operations on the digestive tract from the esophagus through the rectum, together with the liver, gallbladder, pancreas and the abdominal organs that participate directly in digestion. This includes resections such as gastrectomy, colectomy and esophagectomy, bariatric and weight loss procedures such as gastric bypass and sleeve gastrectomy, hepatobiliary and pancreatic procedures such as cholecystectomy, hepatectomy and pancreatectomy, ostomy creation and endoscopic procedures performed within the digestive tract such as endoscopic mucosal resection, and named historical operations such as Billroth I and Billroth II that reorganize the stomach and intestine. General abdominal access procedures that are not specific to one digestive organ, such as exploratory laparotomy, are grouped instead under general and abdominal surgery.