Which device is specifically used to examine the esophagus and stomach?

The device specifically used to examine the esophagus and stomach is a gastroscope. This instrument is designed to allow medical professionals to visually inspect the upper gastrointestinal (GI) tract, which includes not just the esophagus and stomach, but also the duodenum, the first part of the small intestine. The gastroscope is equipped with a light and camera, allowing for clear imaging that aids in diagnosing conditions such as ulcers, tumors, and other abnormalities.

The colonoscope, while also an endoscopic tool, is tailored for examining the colon and rectum, making it unsuitable for inspecting the esophagus and stomach. An endoscope is a broader term that refers to any instrument used to view the interior of a hollow organ, which includes devices like the gastroscope, but it does not specify the region being examined. Ultrasound, on the other hand, is an imaging technique primarily used to visualize soft tissues within the body, rather than directly viewing the inside of the esophagus or stomach. Thus, the gastroscope is the most appropriate and specialized device for this particular examination.