What is the ruling on the yellowish discharges that precede or follow menstruation, and do they prevent prayer and fasting?

Scholars differ on the ruling concerning yellowish and brownish discharges (ṣufratuN and kudratuN). The relied-upon opinion is that they are not considered menstruation unless they occur during the customary period [of menstruation] or immediately follow blood at the end [of the menstrual period].

Accordingly, yellowish discharge before seeing blood is considered menstruation if it occurs during the customary period; otherwise, it is not. However, yellowish discharge that immediately follows blood at the end [of the menstrual period] is considered menstruation.

A woman is not considered to have irregular bleeding (istiḥāḍah) unless the duration of blood flow and any yellowish or brownish discharge connected to it exceeds fifteen days, which is the maximum duration for menstruation according to the majority of scholars.