When is it permissible for a man to have intercourse with his wife if her menstrual period has been prolonged?

Sexual intercourse with a menstruating woman is forbidden by the Qur’an, the Sunnah, and the consensus of Muslims. This prohibition continues until the woman sees purity and performs ghusl (ritual bath). If the bleeding continues for more than fifteen days, the woman is considered to be in a state of istihada (prolonged vaginal bleeding). Intercourse with her is forbidden during the days ruled to be her menstrual period. However, once she performs ghusl after those days have passed, intercourse with her becomes permissible, even if bleeding continues, because intercourse with a woman in istihada is permissible according to the preponderant opinion.