What happened to the stool turning black

Normal stools are yellow soft stools, the surface is not covered with mucus, peptone, etc. The stools become black because of the following reasons: ? 1. Eating animal blood (such as pig blood), animal viscera, etc. causes black stools.? 2. Oral iron, bismuth and other drugs, or Chinese herbal medicines, Chinese patent medicines, etc. cause black stools.? 3. Nasopharyngeal inflammation, nasopharyngeal tumors, etc. cause pharyngeal bleeding, or because hemoptysis and other blood to the pharynx, swallowed into the stomach causes black stools. Four, digestive tract bleeding, especially upper digestive tract diseases caused by bleeding, such as acute gastric mucosal lesions, peptic ulcer, gastric lymphoma, etc., can cause stool color black; small intestine diverticulum, small intestine tumor, small intestine telangiectasia, etc. can show stool black. Five, some systemic diseases cause coagulation disorders, such as acute leukemia, DIC or hemophilia, can cause gastrointestinal bleeding, resulting in stool black.