Ruling 445:
If a woman experiences bleeding and doubts whether it is ḥayḍ or istiḥāḍah, in the event that it has the conditions of ḥayḍ, it must be considered to be ḥayḍ.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)
Purity: Doubt Between Ḥayḍ and Istiḥāḍah
Practical Laws of Islam as per the teachings of Ayatullah Sistani
