OB positive is also known as fecal occult blood positive, fecal occult blood positive is most common in: 1, food. 2, gastrointestinal tract diseases. First, food, pig blood, duck blood, chicken blood and other blood products taken by the body, after digestion and absorption of the digestive tract, and finally excreted out of the body can lead to positive fecal occult blood, which is food-borne. Secondly, some gastrointestinal diseases can also lead to OB positive, such as erosive gastritis, gastric ulcer, duodenal ulcer, ulcerative colitis, etc.. Malignant tumors, such as gastric cancer, colon cancer, etc., are also not excluded. In order to diagnose what gastrointestinal diseases cause OB positive, gastroscopy and colonoscopy should be improved to clarify the specific cause, and then treat the cause.