Before I was diagnosed, I had to do a million tests, including stool samples. I did two tests at the same time: one to look for parasites, the other to look for "hidden" (occult) blood. I thought that was pretty crazy, since there was nothing hidden about it, the blood was right there plain to see everytime I went to the toilet. Oh well, I dutifully went through the motions.
The hardest part I had was collecting a sample of stool at all. I wasn't having anything remotely resembling a stool at that time, it was all bloody mush. Finally I was fed up and just took a sample of the mush. What I had to do was collect it, and using a stick provided, scoop up a bit and put it into a vial containing liquid of some kind, shake it up. So I figured it didn't matter a whole lot if it came from a solid specimen or mush.
The parasite test came back negative, but I'll never forget my doctor telling me in a hushed, solemn voice "They found blood in your stool". NO KIDDING. I did tell her during my initial visit that I had visible blood with bowel movements. Oh well, if that's what it took for her to take it seriously, then I guess it was worth doing it.