The fecal occult blood test can reveal the presence of red blood cells in the stool. If a patient has a dark stool during defecation, a routine stool test can be performed at the hospital. The fecal occult blood test can rule out upper gastrointestinal bleeding. If the fecal occult blood test is (-), it means that there is no bleeding, and if the fecal occult blood test indicates (+), it can be considered to be caused by upper gastrointestinal bleeding. Gastroscopy is also required to be able to look for the site and cause of bleeding, which can be combined with the patient’s clinical condition and in some cases endoscopic treatment. If there is a black color of stool can also be considered to be caused by the situation of diet, in the diet often eat animal liver, chicken blood, pig blood and other blood products or take iron supplementation and other drugs, can also appear false positive performance.