Thank you for the query.
The most common source of fresh blood in stool
are hemorrhoids. If the stool is hard it can rip such hemorrhoids and cause bleeding. Such blood is bright red and on the surface of the stool.
However, before such diagnosis, you have two reasons to have colonoscopy
performed. First are constipations, second is blood in stool. This test should be performed to rule all other reasons of blood in stool including colon polyps and colon cancer
is also advisable.
To prevent constipations you should drink more mineral water, increase fiber rich products, increase physical activity, prevent fatty foods and soft drinks.
Hope this will help.