The possible causes of positive fecal occult blood without white blood cells include peptic ulcer, digestive tract tumor, internal hemorrhoids, digestive tract vascular disease, certain systemic diseases, physiological factors and so on. 1. Peptic ulcer: including gastric ulcer and duodenal ulcer. Peptic ulcer combined with a small amount of active bleeding can cause positive fecal occult blood test without white blood cells. 2. Gastrointestinal tumor: benign tumors including gastric polyps, colorectal adenomas, anal canal polyps, etc. Malignant tumors including gastric cancer, colorectal cancer, anal canal cancer, etc. can cause positive fecal occult blood test when there is a small amount of active bleeding. 3. Internal hemorrhoids: internal hemorrhoids are varicose venous plexus located above the dentate line, due to the mucous membrane epithelium covering the anal canal above the dentate line, it is easy to be damaged and bleed after friction, and it can cause positive fecal occult blood test when the bleeding is small. 4. Gastrointestinal vascular diseases: Gastrointestinal vascular diseases can cause active gastrointestinal bleeding, and there can be no leukocytes when there is no combination of infection or inflammation, for example, intestinal hemangioma, capillary dilatation, intestinal vascular malformations and so on. 5. Certain systemic diseases: certain systemic diseases can also cause a small amount of active gastrointestinal bleeding, such as leukemia, hemophilia, thrombocytopenic purpura and so on. 6. Physiological factors: recent intake of stimulating foods, animal blood products, taking iron factors may cause false positive fecal occult blood test. Patients with positive fecal occult blood but no white blood cells are advised to go to the hospital as soon as possible to find out the cause and treat accordingly.