Stool guaiac test/Fecal occult blood test (FOBT)
Posted by dkwinter

See also:
     Bloody stool Ddx
Causes of false positives
     Ingestion of 
          Red fruits 
          Meats
          Methylene blue
          Chlorophyll
          Iodide
          Cupric sulfate preparations
          Cupric bromide preparations
Causes of false negatives
     Bile
     Ingestion of magnesium-containing antacids or ascorbic acid
Causes of bloody-looking stool
     Red Jell-O
     Tomato sauce
     Wine
     Iron therapy
     Pepto-bismol