Why do I need to do blood 3 times?

Fecal occult blood is an early warning of gastrointestinal abnormalities. When gastrointestinal bleeding is small and abnormal stool manifestations cannot be recognized by the naked eye, fecal occult blood examination should be performed on patients with chronic gastrointestinal bleeding. Early screening for gastrointestinal malignancies, gastric cancer, colorectal cancer and polyadenomas is also important. If stool examination has hidden blood conditions, symptoms of gastrointestinal bleeding should be considered. The positive rate of peptic ulcer is 40%~70%. When digestive tract cancer such as gastric cancer, the positive rate can reach 95% long continuous positive, other diseases caused by gastrointestinal bleeding can also be positive. Early trace bleeding of digestive tract malignant tumor may be the only symptom, so occult blood test is the only effective means of early detection of digestive tract tumor. If routine stool examination detects occult blood, it is recommended to test qualified patients three times in succession to improve the positive rate.