Praise be to Allah, and we ask Allah to raise the rank of Prophet Muhammad peace be upon him and to protect us from the misguidance and to purify our hearts and grant us the sincere intentions ameen.

Scholars say: It’s essential for the Muslim to learn about the purification from impurities such as menses. Three types of blood come from the woman’s vagina and each has judgments pertaining to it. They are the menses, lochial blood, and dysfunctional uterine bleeding/pseudo menstruation/chronic bleeding.  

The menstrual blood is the blood that exits from a woman’s vagina at a minimum age of 9 lunar years or 16 days before attaining that age. It comes from the inner part of the uterus. It can be seen in 5 colors, the strongest of which is black (due to the intensity of its redness), followed by red, then a weaker shade of red, then weaker, and the weakest.

The postnatal bleeding is the blood that exits within 15 days of giving birth; in fact it is blood that exits following the clearing of the uterus. The blood that exits after an embryo or a fetus (mudgha or alaqa) ie a miscarriage is lochial blood if a the origins of a human were apparent in the exiting flesh.

The dysfunctional uterine bleeding is blood that exits during cleanliness days, that is not days of menses or postpartum bleeding. It comes from a vein in the foremost part of the uterus.

The minimum allotted time for the menstrual blood is one day and night ie 24 hours. Once a woman sees blood, after the passage of at least 15 days of purity, she stops praying. She does not wait for 24 hours to pass before she stops praying. However, if the blood stops before 24 hours it would not be considered as menstruation, rather it is chronic bleeding and she does not take the ritual bath after it. She is also obligated to make up the prayers that she left out during that time.   

If the blood came out in interrupted intervals but the total time if the intervals were added would be 24 hours during a time period of 15 days then it is considered menstruation. For example, during the first day she say blood for 1 hour, the second day 5 hours, the third 7 hours, the fourth 10 hours, and the fifth 1 hour. once that hour ends she knows that this entire period was her menses because within 15 days it reached 24 hours and she knows that her prayer during that time was not valid. Each time she sees blood she treats it according to the situation. Initially, she considers it menstruation when the blood stops she prays when it returns she stops praying and so on until reaching 24 hours. At that point she knows that the entire time was her menstruation.

The maximum length of menstruation is 15 days. Blood exceeding 15 days is considered chronic bleeding and has its own rules and details associated with it.

Summary
There can be no menstruation for a female younger than approximately 9 years old
The minimum time menses is 24 hours within a period of 15 days
The maximum is 15 days and what exceeds that is chronic bleeding
The minimum length of purity is 15 days, hence any blood seen before that period is attained is chronic bleeding and treated as such

When a woman sees blood after the passage of the minimum days of purity, she stops praying. If the blood started during the time of a prayer in which there was enough time to perform that prayer, then she must make up that prayer.

Once the blood stops, after reaching the minimum required time, she must take a ritual bath and commence praying. If her blood stops during the time of a prayer and while having enough time to say Allahu Akbar in that prayer, she must make up that prayer. Additionally she makes up the one before it if they are combinable prayers. That means if her bleeding stops during Asr with enough time to say Allahu Akbar she must make up both Asr and Dhuhur. If it stops during Isha with enough time to say Allahu Akbar she makes up both Isha and Maghrib.

During the menses or neonatal bleeding the woman is not allowed to:
Pray
Make circumambulation (tawaf) around the Kabah
Touch or recite the Quran
Remain in the mosque
Fast, before the cessation of blood
Allow her husband to have sexual intercourse with her
After the ritual bath, a woman may do all of the aforementioned.