PillCam is a capsule-sized miniature camera that lets doctor see the inside of your intestines esophagus:
The patient swallows the capsule lying down, and is then raised in a series of inclinations over a total of 5 minutes. The PillCam™ ESO travels through the esophagus by normal peristaltic waves, flashing 14 times per second, each time capturing images of the inner lining of the esophagus.
As it continues down the esophagus, the images captured may identify potential abnormalities, such as Esophagitis - which is inflammation of the lining of the esophagus often caused by Gastroesophageal Reflux Disease or GERD. Severity of symptoms is measured by a Grading system, and in severe cases, esophageal ulcers can appear.
Link - via SCI FI Tech