Which procedure uses a scope to examine the lower part of the small intestine, including the sigmoid colon?

• A. Sigmoidoscopy
• B. Colonoscopy
• C. Endoscopy
• D. Upper endoscopy

Answer: (A)

Using a scope to view the lower gastrointestinal tract is done with a colonoscope. This instrument is inserted through the rectum and advanced through the entire colon, allowing visualization of the lining from the rectum up to the sigmoidal region and often beyond to the cecum (and sometimes even the terminal ileum at the end of the small intestine). Sigmoidoscopy, by comparison, reaches only the rectum and sigmoid colon, so it doesn’t survey the rest of the colon or the small intestine. Endoscopy, when specified as upper endoscopy, targets the upper GI tract (esophagus, stomach, and duodenum), not the lower GI. So for examining the lower GI tract including the sigmoid colon, colonoscopy is the appropriate choice.