Must the questioner fast the remainder of Ramadan or break her fast and make up for it later, knowing that her menstruation began with a very small amount, continued for thirteen days, then its quantity increased, bringing the total period to fifteen days and still ongoing, and she suffers from polycystic ovary syndrome and irregular menstruation, and she does not know whether this is menstruation or istihadah (non-menstrual vaginal bleeding)?

The jurists differed on the maximum duration of menstruation. The preponderant view is that there is no maximum limit for it, and this is the choice of Ibn al-Mundhir, Ibn Taymiyyah, and a group of scholars. The default is that the blood that a woman experiences is menstrual blood unless it covers the entire month or stops for only one or two days. Ata’, Al-Shafii, Ahmad, and Abu Thawr held that its maximum duration is fifteen days, while Sufyan al-Thawri, al-Numan, Yaqub, and Muhammad held that its maximum duration is ten days. A group said that there is no minimum or maximum limit for menstruation in terms of days. Menstruation is the blood that is distinct from Istihadah blood. So, the blood that a woman sees is menstruation, even if it exceeds fifteen days, especially with irregular cycles and the presence of polycystic ovaries.