Some people describe turning the toilet bowl red, while others are like Eva Lou - "sometimes it's just on the TP, other times it's on the stool, sometimes it's little bloody pieces of mucous in the toilet." I fall into Eva Lou's category, although right now I don't have a bleeding problem, just really sharp pains, gas, and other annoying discomforts.
If you are really concerned, talk with your GI doc. The more open you are about stuff the better your treatment will be. I used to be hesitant about discussing this stuff with doctors (not socially acceptable), but then it occurred to me that my doc has heard it all before, and I wasn't in his office to shoot the breeze, I was there to get rid of the very things I didn't want to talk about!
36 y.o. male
Diagnosed w/ UC in May '06, had symptoms since '99
Meds & supplements: VSL#3, Lialda, Allegra, multi-vitamin, Wellbutrin XL, Prednisone, fluoxetine, flaxseed oil, magnesium, and vit B-12.