Normal colonoscopy but blood in stool, what's wrong?

See below : The colon is so huge that sometimes the camera doesn't catch a small bleed. Colonoscopies are important to make sure you don't have inflammation in the colon and it rules out serious causes. You might have a blood vessel that bleeds on and off. Or it might be something in the anal area like a crack in the wall causing some bleeding when you wipe. Also the bleed could be from above the colon.