Which examination uses a thin fiberoptic scope to view the upper gastrointestinal tract through the mouth?

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

Answer: (C)

The concept being tested is identifying the procedure that uses a thin, flexible scope passed through the mouth to examine the upper gastrointestinal tract. This approach allows direct visualization of the esophagus, stomach, and the first part of the small intestine (the duodenum) with the scope guided down from the mouth. The term that specifies this region and method is upper endoscopy (also known as gastroscopy or esophagogastroduodenoscopy). Other procedures listed target different parts of the GI tract: sigmoidoscopy and colonoscopy examine the lower GI tract via the rectum, while endoscopy is a broad term that can refer to examining various parts of the body, not specifically the upper GI tract. Therefore, upper endoscopy is the correct description for a thin fiberoptic scope viewed through the mouth into the upper GI tract.