Abnormal menstrual flow
Menstrual blood is a natural hormonal flow of blood with no physical cause. Blood that has a physical cause is not menstruation. This means that the secretions that come out if the doctor confirmed that it is caused by IUD, for example, then it is not menstruation.
As for the brown yellowish stains, they are not part of menstruation. Menstruation is the dark blood flow with odor, which is thick and dark.
Accordingly, the days of the menstrual cycle are days during which a woman experiences the flow of the known dark blood. Anything outside that are secretions not menstruation. It is therefore necessary for her to perform ablution at every salah (prayer).