What is the ruling on continuous yellowish discharge after menstruation, and is it considered istihada ( метроrhagia), knowing that the original duration of menstruation ranges between 9 and 13 days?

A woman experiencing istihadah (non-menstrual vaginal bleeding) should follow her previous habit if she remembers it. Otherwise, she should rely on discernible characteristics of the blood, provided it does not exceed fifteen days. If she cannot distinguish the blood, then her menstruation is considered to be the most common habit of women (six or seven days), and anything beyond that is istihadah.