Women experience different patterns of menstruation. Women generally experience regular menses that last for a certain period of time. Some women may experience extended menstrual bleeding that exceeds the average period of time, while others may be perplexed by untimely menses. Each of these categories has its own ruling.
Sheikh Ahmad Kutty, senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Canada, stated, In the case of chronic bleeding, it is important for a lady to know what pattern of menses she had before the beginning of this condition. In other words, if she had a pattern of menstruation that lasted for six or seven days, then she should reckon the same number of days as belonging to the menses and assume that what comes after belongs to istihadah, where she ought to resume Prayers after performing ghusl (ritual cleansing of the body).
There is, however, one important condition for her to observe: A lady undergoing this condition should clean herself and make fresh wudu’ (ablution) for each of the Prayers she performs. She should do so immediately prior to the Prayer she is intending to perform.