The preparations before gastroscopy are as follows: 1, gastroscopy: if it is common gastroscopy, 2 hours of water fasting, 6 hours of fasting, and more than 8 hours of fasting if you eat greasy food. In case of painless gastroscopy, 4 hours fasting is required; 2. Colonoscopy: 2 days before the examination, indigestible foods such as kelp, green vegetables with high fiber content, fruits containing seeds or kernels, etc. should be avoided. Therefore, it is recommended that patients should consult their doctors before performing gastroscopy and strictly follow the relevant precautions to avoid wrong test results.