What should i avoid prior to taking the stool blood test?

Bismuth and Iron: Generally, if you can, you should avoid medications that contain bismuth such as pepto-bismol & iron tablets/pills for a few days. This is because it can stain the stool black & sometimes give a false positive reading on the fecal occult-blood test (fobt). If you're on blood thinners such as coumadin, (warfarin) aspirin, or plavix, let the doctor ordering your test know too but don't stop unless told to.

Red meat: The tests are very sensitive for blood in your stool and if you eat red meat it may be a false positive as the "blood" would be from the red meat and not your bowels.