Should one verify purity from menstruation before or after washing the area, knowing that upon verification before washing there are traces of menstruation, and after washing there is nothing?

Purity is confirmed by the complete dryness of the exit before washing it. This is done by passing a tissue over the outer vulva before washing it. If it comes out dry with no trace of menstrual blood, that is a sign of purity. However, if the area is washed before this check, the trace of blood may disappear with the water, and purity will not be confirmed. The signs of purity are complete dryness or the discharge of the white secretion (al-qassah al-bayda’). As long as a woman finds traces of blood when passing the tissue, this indicates impurity. Dryness means inserting cotton or a cloth into the vagina and it coming out dry with no blood on it.