Purity: Types of Istiḥāḍah

Practical Laws of Islam as per the teachings of Ayatullah Sistani

Ruling 391:

There are three types of istiḥāḍah: slight (qalīlah), medium (mutawassiṭah), and excessive (kathīrah).

Slight istiḥāḍah is when the blood only stains a piece of cotton [or the top layer of a sanitary pad/another absorbent item] and does not seep into it.

Medium istiḥāḍah is when the blood seeps into a piece of cotton [or top layer of a sanitary pad/another absorbent item] that a woman would normally use to absorb the discharge of blood – albeit into only one side of it – but it does not reach the bottom of it.

Excessive istiḥāḍah is when the blood soaks a piece of cotton [or sanitary pad/another absorbent item] and reaches the bottom of it.

-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)