A 48-year-old woman’s 20-day unclean period may be caused by a variety of reasons, such as menopause, menstrual disorders, low hormone levels and so on. It is recommended to go to the hospital for a targeted gynecological examination to identify the specific cause and then treat the cause. 1. After the age of 45, women’s ovarian function begins to decline and they may gradually enter menopause. The decrease in ovarian and uterine capacity at the onset of menopause may lead to menstrual abnormalities, and menstruation is easily disrupted after menopause, and there may be vaginal bleeding for more than ten consecutive days. 2. It may be caused by uterine lesions, especially endometrial hyperplasia, fibroids and other conditions, which may lead to an increase in menstrual flow and even prolonged menstrual period. 3. A greater decrease in the level of sex hormones can also lead to irregular menstruation and prolonged menstrual cycles. Therefore, once you have prolonged menstrual cycles and you are in menopause, it is recommended that you seek medical attention in time to avoid delaying your condition.