Blood in stool 15 days after colonoscopy may be due to intestinal injury, hemorrhoids, intestinal tumor, which can be treated by general treatment, medication and surgery. 1. Bowel injury: when performing colonoscopy, it may cause damage to the intestinal mucosa, which may cause a small amount of bleeding. It causes blood in the stool. This kind of damage can be recovered through the body’s self-repair, during this period should avoid eating stimulating food, can use bifidobacteria under the guidance of the doctor to relieve the treatment. 2. Hemorrhoids: hemorrhoids can also cause blood in the stool, patients should avoid constipation, while avoiding prolonged sitting and squatting, you can apply hemorrhoid cream, erythromycin ointment and other treatment under the guidance of the doctor, if the symptoms are more serious, you need to go to the hospital for hemorrhoidectomy. 3. Intestinal tumors: Intestinal tumors can also cause blood in stool, such as rectal tumors, colon tumors and so on. Tumors usually need to be removed through surgery to achieve the purpose of treating the disease. Blood in stool 15 days after colonoscopy is also seen in other reasons, patients should seek medical examination and treatment in time to avoid delaying the condition.