Digestive Diseases and Endoscopy Endoscopy is a medical procedure used to diagnose and treat digestive diseases. There are two main types of endoscopy: upper endoscopy and colonoscopy. People with gastrointestinal symptoms often need to undergo upper endoscopy. On the other hand, colonoscopy is used to diagnose colorectal cancer and other bowel conditions. Read more about the benefits and costs of endoscopy in Singapore.