Jane Bradley, age 13, of Orlando, Fla., for her question:

HOW DOES A GASTROSCOPE WORK?

A gastroscope is an instrument doctors use to look at the inside of the stomach. It has two main parts: a rigid portion with several lenses and a long; flexible portion that has lenses and prisms.

The gastroscope has a soft rubber tip and a small electric light to illuminate the stomach. Special attachments are made for some gastroscopes. One type permits a camera to be attached so that pictures can be taken of the stomachs interior.

in the stomach and to diagnose such conditions as peptic ulcer, gastritis and stomach cancer. Not all areas of the stomach can be seen with a gastroscope, but the instrument may provide information that cannot be obtained by other means.

A patient must not eat anything before an examination so that the stomach will be empty. A local anesthetic is passed through the mouth into the stomach. The doctor then inflates the stomach with air so its lining can be seen more easily.