Which procedure uses a scope to examine the entire colon (large intestine)?

• A. Endoscope
• B. Endoscopy
• C. Sigmoidoscopy
• D. Colonoscopy

Answer: (D)

Colonoscopy uses a long, flexible scope (a colonoscope) threaded through the rectum to visualize the entire length of the large intestine, from the rectum through to the cecum. Because it is designed to reach all segments of the colon, it can survey the entire colon in one procedure and allows biopsies or removal of polyps if needed.

An endoscope is the instrument itself used in endoscopy, which can examine various parts of the digestive tract but not necessarily the entire colon. Endoscopy is the general category of procedures that use scopes. Sigmoidoscopy, by contrast, reaches only the sigmoid portion of the colon, so it does not examine the entire colon. Therefore, the procedure that examines the whole colon is colonoscopy.