The most common diagnostic test for gastritis is endoscopy with a biopsy of the stomach. The doctor will
usually give the patient medicine to reduce discomfort and anxiety before beginning the endoscopy procedure.
The doctor then inserts an endoscope, a thin tube with a tiny camera on the end, through the patient’s mouth
or nose and into the stomach. The doctor uses the endoscope to examine the lining of the esophagus,
stomach, and first portion of the small intestine. If necessary, the doctor will use the endoscope to perform a
biopsy, which involves collecting tiny samples of tissue for examination with a microscope.