Blood associated with a bowel movement [without loose stool] can be both visible and invisible to the naked eye. Many times another disharmony, such as dizziness, low blood pressure, paleness, fatigue or anemia, may be a clue to understanding the nature of the chronic loss of blood.
Blood loss may also come from high above such as with your stomach or in the lower region such as with your large intestine [chronic hemorrhoids]. Usually the case is, the higher the source of the bleeding, the darker the color of the blood.
Any sign of blood, or its associated disharmonies, should require a visit to your doctor to rule out something as severe as cancer [polyps] or vascular disease. Once ruled out, there are many Chinese Medicine Patterns and Chinese Herbal Formulas that can prove to be very helpful in resolving blood loss through your stools.