Before gastroscopy, you need to check the blood routine, coagulation function, liver and kidney function, electrocardiogram and so on. 1. Blood routine: it is a routine examination item, mainly to check whether the patient has anemia and blood system diseases. 2. Coagulation function: to clarify whether there is any coagulation dysfunction to avoid hemorrhage during gastroscopy. 3. Liver and kidney function: liver function is mainly to test the amount of transaminase in serum, to clarify whether there is hepatocellular damage; while kidney function test is mainly to check whether there is kidney disease and the severity of kidney disease. 4. Electrocardiogram: mainly some elderly patients and patients with cardiovascular disease should do electrocardiogram before gastroscopy to exclude the presence of heart disease. Other tests may be needed before the gastroscopy, depending on the patient’s own condition, but always consult your doctor first and be well prepared for the examination.