Which procedure allows for the direct visual examination of the inner surface of the entire colon?

The procedure that enables direct visual examination of the inner surface of the entire colon is a colonoscopy. This minimally invasive procedure involves the use of a flexible tube equipped with a camera, known as a colonoscope, which is inserted into the rectum and advanced through the entire colon. It allows healthcare providers to directly visualize the lining of the colon, identify abnormalities such as polyps, tumors, or inflammation, and even perform diagnostic procedures like biopsies or polypectomies during the same session.

In contrast, esophagoscopy is specific to examining the esophagus, often used for diagnosing conditions related to swallowing, while barium studies utilize X-rays and a barium contrast solution to highlight the gastrointestinal tract but do not allow for direct visualization. Palliative surgery is generally aimed at relieving symptoms rather than diagnostic examination of the colon. Therefore, for the purpose of visual examination of the colon itself, colonoscopy is the definitive procedure.