The difference between true black stool and false black stool is the clinical history, stool characteristics and laboratory tests.
1. Clinical history: True black stools are usually associated with underlying diseases such as gastric ulcer and cirrhosis of the liver, which may cause gastrointestinal bleeding. Most patients with pseudo-black stools do not have such medical history, but may have a history of taking drugs such as iron and bismuth, or consuming dietary conditions such as duck blood or pig blood.
2. Stool characteristics: True black stools are usually black but shiny, and can be soft, dilute, or pasty, and are usually accompanied by bright red or dark red blood. False black stools usually do not have the above characteristics and are mostly soft.
3. Laboratory tests: fecal occult blood test is mostly positive in true black stools, and gastrointestinal bleeding can also be detected in imaging or endoscopy. The above tests are mostly negative in false black stools.
If the patient has black stools, it is recommended to consult a doctor for timely and targeted treatment under the guidance of the doctor.