Fecal occult blood
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![A positive traditional guaiac fecal occult blood test](/Images/godic/202501/30/Positive_fecal_occult_blood_test5902.jpg")
Fecal occult blood (FOB) refers to blood in the feces that is not visibly apparent (unlike other types of blood in stool such as melena or hematochezia). A fecal occult blood test (FOBT) checks for hidden (occult) blood in the stool (feces). Newer tests look for globin, DNA, or other blood factors including transferrin, while conventional stool guaiac tests look for heme.