The methods of recognizing bloody stools include visual observation and laboratory tests. 1. Visual observation: Generally, bloody stools will be accompanied by black stools or fresh blood stools, which can be identified by this method. If the amount of bleeding is relatively large, there will be blood visible to the naked eye, which is easy to observe; if the amount of bleeding is relatively small, there may be black stools, which can not be distinguished due to the influence of food or medication, and generally require laboratory tests. 2. Laboratory tests: blood that is not visible to the naked eye can be examined by fecal occult blood test, in addition to routine stool examination, fecal bacterial culture, parasite detection, blood test, liver and kidney function tests and other laboratory tests to assess the bleeding situation. Generally, bloody stools are caused by gastrointestinal bleeding, hemorrhoids, gastrointestinal tumors and other diseases, which can be life-threatening. Once you have bloody stools, it is recommended to consult a doctor in time, complete the relevant examinations to clarify the cause of the bleeding, and treat it in time so as to avoid delaying the condition.