Have occasional red blood in stool. usually happens with a large stool that can be painful when passing but not constipated. dr did a sigmoidoscopy and says he sees nothing wrong at all. possible???

Irritation at anus: A large painful stool can cause irritation at the very end of the rectum causing bright blood to be seen in the stool. Eating more insoluble fiber- in whole grains and vegetables -with plenty of fluids, will help the stool become softer and pass more easily. Consider more- wheat bran, corn bran, seeds, nuts, zucchini, celery, broccoli, cabbage, onions, tomatoes, carrots, cucumbers, green beans,

May be a fissure: If this occurs with a large stool and no hemorrhoids were seen then consider a fissure (or tear of skin). These can heal rapidly so your doctor may not see it when you get checked. They often can be itchy while healing. If this sounds possible, a stool softener may help even if you are not constipated.