You need to fast for 6 to 8 hours before the gastroscopy, and patients who smoke and drink need to abstain from smoking and alcohol for a period of time. The diet of the day before the gastroscopy needs to be based on easy-to-digest food. Gastroscopy is a commonly used clinical examination method, which, with the help of a flexible tube, allows the doctor to visualize lesions inside the upper gastrointestinal tract. Pathologic biopsy can also be performed on suspected lesions to help doctors further diagnose the disease. It is by far the preferred test for upper GI lesions. However, it should be noted that patients with severe heart and lung disease should not undergo this test. Because gastroscopy involves looking into the lining of the digestive tract and collecting tissue, it requires the patient’s stomach to be in a state of emptying when this test is performed. Patients are usually asked to eat an easy-to-digest diet the day before the gastroscopy and to fast for 6 to 8 hours before the gastroscopy. Cigarettes and alcohol can irritate the stomach lining, so patients who smoke and drink need to abstain from smoking and alcohol for a period of time. If you have pyloric obstruction, you will need to undergo gastrointestinal decompression before the examination to empty the stomach contents. If there is a need for gastroscopy, it is important to communicate with the doctor in advance and make all the pre-test preparations to avoid risks during the examination.