Does a stool culture test for blood? My doctor sent away for one, and I brought one in the office and he did a smear on a card. My diet pretty much stinks, and I'm often dehydrated. I notice that when I increase my water intake, my stools are easier to pass, but still pellets. Do you think my chances of colon cancer are less because of the strict "fruits-and-vegetables" diet I went on last month for a couple of days and my stools were "normal" from bristol stool chart?