2,059. Only Blood
Hilchos Issurei Biah 5:5
Blood from the “room” is always ritually unclean except for the pure blood after giving birth and the bleeding that occurs before birth, which will be explained. Blood from the “upper level” is ritually clean, the same as blood from a wound that one might have in the intestines, liver, kidneys, etc. If blood from the “anteroom” is found between the “passage” and the uterus, the woman is rendered ritually unclean because we assume that it came from the “room.” A woman would be liable if she entered the Temple in this state, and tithes and sacrificial meat must be burned because of it. We do not suggest that it might have come from the “upper level” because most blood found there comes from the “room.” If blood is found in the “anteroom,” the woman is rendered ritually unclean out of doubt, i.e., the blood may have come from the “room” or from the “upper level” by way of the “passage.” Because of the doubt, tithes and sacrificial meat aren’t burned and a woman isn’t liable for entering the Temple.
Hilchos Issurei Biah 5:6
Not every liquid from the “room” renders a woman ritually unclean; only blood has this effect as per Leviticus 15:19, “a discharge of blood.” Accordingly, if woman experiences a white or a green discharge from her uterus, even if it’s the consistency of blood, she remains ritually clean because it doesn’t look like blood.