If the black stool is caused by gastrointestinal bleeding, the naked eye can see that the color of the stool is black, this situation suggests that the daily bleeding amount is more than 50ml, as follows: 1. If the color of the stool is not black when observed by the naked eye, but the laboratory stool suggests that the occult blood test is positive, this situation suggests that the gastrointestinal bleeding is more than 5ml, but less than 50ml; 2. If the bleeding is more urgent, the bleeding amount is larger, and the stomach When the amount of accumulated blood exceeds 250ml, the patient can show symptoms of vomiting blood; 3. When the patient bleeds less than 400ml at one time, there is only a mild reduction of blood volume, which can be supplemented by tissue fluid and blood stored in the spleen, and the patient mostly has no systemic symptoms; 4. When the amount of bleeding exceeds 400ml, the patient can show symptoms of insufficient effective circulating blood volume such as dizziness, palpitations and weakness; 5. If bleeding volume exceeds 1000ml in a short period of time, the patient may show signs of hemorrhagic shock. In case of these conditions, patients are recommended to go to the regular hospital for consultation and relevant examination in time. When the bleeding volume is large, hospitalization is required, and blood transfusion can also be done in time to ensure life safety.