After cholecystectomy surgery, if the patient has black stool, it may be physiological reasons or pathological reasons, such as gastrointestinal bleeding. 1. Physiological reasons: it is due to eating foods such as iron, duck blood, etc. Containing iron produces iron sulfide under the action of bacteria in the intestinal tract, which will affect the color of the stool and appear as black stool. 2. Pathological causes: (1) Biliary hemorrhage: if there is biliary injury during the operation and it fails to stop bleeding exactly, it may cause postoperative biliary hemorrhage, which flows into the intestine and causes black stool. (2) Gastric disease disease: cholecystectomy may affect gastric digestion, diarrhea or indigestion. It may cause gastric diseases such as acute gastritis, stress ulcer, etc. When there are bleeding spots at the lesion site, it will make the stool black in color as the blood undergoes oxidation in the intestines. (3) Blood diseases: patients themselves suffer from blood diseases, such as hemophilia, active thromboplastin generation disorders, prolonged coagulation time, when there are bleeding spots in the gastrointestinal tract, it is easy to form black stool. When black stool occurs after cholecystectomy surgery, it is recommended to consult a doctor in time, follow the doctor’s instructions for further examination, clarify the cause with the help of the doctor, and carry out targeted treatment or therapy.