On whether chronic colitis stools will definitely have blood, as follows: 1, chronic colitis ulcers may appear when they are larger, generally will not appear flesh blood; 2, stool routine examination of occult blood test positive does not necessarily appear, because chronic colitis is only congestion edema, intestinal mucosa without erosion, exudation, bleeding, stool occult blood is negative. If the chronic colitis is more serious, the damage to the colonic mucosa is more serious, erosion or even ulceration can occur, and the ulcerated surface will bleed, then the stool routine examination will appear positive for occult blood. If the stool is positive for occult blood, you must go to the hospital for a review and do related tests, such as colonoscopy to determine whether there is chronic colitis or colon polyps or colon tumors. Colon tumors are very prevalent, so it is important to pay attention to routine stool examination, which is very necessary.