Are the discharges that precede menstruation by ten days or more impure and considered part of menstruation?

If the discharge does not resemble yellowness or turbidity, then it is not considered menses, but it does invalidate ablution. However, if it has the color of yellowness or turbidity and occurs during the period when menstruation is possible (after fifteen days of purity, and it connects with menstruation, and the woman feels its symptoms), then it is considered menses. If the days of menstruation, along with the days of bleeding, exceed fifteen days, then the woman is considered to be experiencing istihada (prolonged vaginal bleeding), and she should then differentiate between menstrual blood and other blood, or revert to her regular monthly habit if she cannot differentiate.