How can one determine the sign of purity if the discharges are always yellowish, there is no sign of dryness after the menstrual period, the yellowish discharges persist throughout the month, and the white discharge (al-Qassah al-Bayda’) is unknown?

The maximum duration for menstruation is fifteen days. If the blood, along with any connected yellowish or brownish discharge, exceeds this period, the woman is considered to be experiencing irregular bleeding (istihadah).

In this case, if the woman can distinguish between black blood as menstruation and yellowish discharge as irregular bleeding, then her menstruation ceases with the cessation of the red blood. She should perform ghusl (ritual purification bath) and pray. During the period of yellowish discharge, she takes on the rulings of a woman experiencing irregular bleeding: she performs ablution (wudu) for each prayer after its time has begun, and she may pray both obligatory and supererogatory prayers with that ablution until the time for that prayer exits. This continuous yellowish discharge is impure, and one must take precautions against it.