Which examination allows for viewing the esophagus, stomach, and upper duodenum through a flexible scope?

The examination that allows for viewing the esophagus, stomach, and upper duodenum through a flexible scope is gastroscopy. This procedure, also known as esophagogastroduodenoscopy (EGD), involves inserting a flexible tube with a camera, called an endoscope, through the mouth and down the throat, allowing the physician to visualize these upper gastrointestinal structures directly. Gastroscopy is primarily used to diagnose conditions such as ulcers, inflammation, tumors, and bleeding as well as to perform therapeutic interventions, like biopsies or foreign body removal.

In contrast, sigmoidoscopy focuses on examining the lower part of the colon (the sigmoid colon), and proctoscopy specifically examines the rectum. A nuclear medicine study involves imaging techniques using small amounts of radioactive materials to assess various body functions and is not related to the direct visual examination of the gastrointestinal tract.