How can one differentiate between menstrual blood and abnormal bleeding (istihada), and what are the resulting rulings concerning ritual bathing (ghusl) and prayer, given continuous bleeding for prolonged periods due to cysts?

If menstrual bleeding continues for more than fifteen days, the woman is considered to be in a state of istihadah (non-menstrual vaginal bleeding), and her ruling varies depending on her situation:

1. If the woman had a regular menstrual cycle before the istihadah: She observes her usual days of menstruation, then performs ghusl (ritual bath) and prays, as the Prophet, peace and blessings be upon him, commanded Fatimah bint Abi Hubaysh. 2. If she did not have a regular cycle or forgot it: She relies on distinguishing between menstrual blood and istihadah blood by its color, smell, and consistency. Menstrual blood is black or dark and has an odor. These days are considered menstruation, then she performs ghusl and prays. 3. If she has no regular cycle and no valid distinguishing characteristic: She observes six or seven days, which is the common duration of menstruation, then performs ghusl and prays.

For the distinguishing characteristic to be valid, the distinguished blood must be suitable to be menstrual blood, meaning it should not be less than one day and one night nor exceed fifteen days. If the distinguishing period is less than one day and one night, it is not considered, and the woman reverts to the common duration of menstruation (six or seven days).