The formation of black stool may be caused by either upper or lower gastrointestinal bleeding, and gastroscopy is not able to fully determine the cause of black stool.
The causes of black stool are related to upper gastrointestinal bleeding, such as gastric ulcer, gastric cancer, rupture and bleeding of esophagogastric varices, etc. The causes of black stool are related to lower gastrointestinal bleeding, such as intestinal ulcer, intestinal cancer, etc., which can also lead to the formation of black stool.
Gastroscopy can only determine whether there is bleeding in the stomach, but not in the intestines, therefore, gastroscopy cannot fully determine the cause of black stool, but if combined with gastroenteroscopy, it can determine the cause of black stool. If there is black stool, excluding dietary factors, it is recommended to consult a doctor in time to clarify the cause of black stool, targeted treatment.