Digestive system examinations, most commonly gastroscopy and colonoscopy, are performed. As the name implies, gastroscopy is an examination of the upper gastrointestinal tract and usually reveals gastritis, peptic ulcers, tumors, polyps, etc. Colonoscopy is to examine the colon, and during the examination, inflammation, polyps, tumors and other lesions are usually found. There are also blood tests, mainly to check liver function, which are also part of the digestive system tests. There are also some tumor markers, such as carcinoembryonic antigen, methemoglobin, CA125, CA199 and other tumor markers of the gastrointestinal tract. There are also imaging examinations, which may include ultrasound, CT or MRI of the liver, biliary and pancreatic tracts and pancreas, which are all part of the digestive system.