How long is the menstrual period if the blood started last Saturday and continued until Thursday night?

When a woman sees blood, she is menstruating, and she continues to be in menses until she sees purity by one of its two signs: complete dryness or the white discharge. A woman is considered to be menstruating as long as her menstrual period does not exceed fifteen days. If the blood exceeds this duration (including any intermissions), we know that the woman is experiencing irregular bleeding (istihadah (definition)). If she sees blood for the period mentioned in the question (six days) and thirteen days or more have passed since the end of the previous menses, then all those days are considered menstruation. The custom (of a woman's period) may increase or decrease, or come earlier or later, and the determining factor is the time when menstruation is possible.