A puddle of bright red blood in the stool may be caused by hemorrhoids, anal fissure, rectal cancer and other diseases. 1. Hemorrhoids: Hemorrhoids is a common anal disease, according to the occurrence of different parts can be divided into internal hemorrhoids, external hemorrhoids and mixed hemorrhoids. Due to the varicose veins in the anal canal, when defecating, fecal matter damages the varicose hemorrhoidal veins, which can lead to the symptom of blood after defecation, and there is usually no pain symptoms. 2. Anal fissure: when anal fissure occurs, there will be severe pain and accompanied by blood in stool, which must go to the hospital for diagnosis and treatment. 3. Rectal cancer: it is a common type of cancer, and its incidence is hidden, mostly in the late stage when it is detected, so it is necessary to pay attention to vigilance. If you have a puddle of bright red blood in the stool, there may be other reasons, so you need to go to the hospital for examination, clarify the cause of the disease, and follow the doctor’s instructions for treatment, so as to avoid delaying your condition.