Acetic Acid Chromoendoscopy to Judge Gastric Intestinal Metaplasia

The presence and the extent of gastric intestinal metaplasia(IM) is a good indicator of high risk group of gastric cancer. Many methods was developed to survey it, including multiple gastric biopsy or methylene blue chromoendoscopy. But they are not practical in the routine screening exam, limited by cost and accessibility. Spraying of acetic acid is commonly used in screening cervical cancer, to induce whitish discoloration of metaplastic mucosa. The investigators have confirmed such whitish discoloration is induced in gastric IM, with accuracy \> 80% in a pilot study of the investigators. This prospective study will tell the accuracy, sensitivity and specificity of acetic acid chromoendoscopy for judging gastric IM.