Gastroenteroscopy done on the same day is usually not very harmful and the harm to the body is generally small, but some patients cannot tolerate it and may experience abdominal pain and bloating, nausea and vomiting and other discomforts. Gastroscopy is to insert the gastroscope from the oral cavity through the esophagus to the stomach, to observe the lesions of the gastric mucosa; enteroscopy is to insert the enteroscope from the anus, through the rectum to the ileum, to observe the mucosal lesions of the rectum, colon and other places. Theoretically, there is no conflict between the two examinations on the same day. However, since both gastroscopy and colonoscopy are invasive tests and require the injection of a certain amount of gas into the digestive tract, if both tests are performed on the same day, patients may experience significant abdominal pain and bloating, nausea and vomiting, and other discomforts. Although the harm caused to the body is not significant, some patients may find it difficult to tolerate, to the detriment of the examination. Therefore, even if gastroenteroscopy does not cause much harm to the body, patients who need to undergo gastroenteroscopy should follow the doctor’s arrangement and conduct the examination reasonably.