The zatu 'I-'adah women in groups (a) and (b) have to observe the rules of menstruation as soon as they see the blood. It makes no difference whether it starts on the fixed day, or one or two days before it or after it, even if it does not have all the three signs of menstrual flow. Of course, if she discovers that it was not menstruation (for example, the blood stopped on the second day), then she will have to perform her salat (which she had missed during the two days) as qaza.

The zatu 'l-adah women in group (c) have to observe the rules of menstruation if the blood has all the three signs of menstrual flow mentioned above. If the discharge does not have all the three signs, then it will not be regarded as menstruation.

When a zatu 'l-'adah woman sees blood many days before or after the fixed time then if it has the three signs altogether, it is menstruation; otherwise it will be regard­ed as istihazah.

with 3 signs = hayz.
without 3 signs = istihazah.

with 3 signs = hayz. without 3 signs = istihazah.

But as mentioned above, if a zatu 'I-'adah woman sees blood during the fixed time, it is hayz even if it does not have the three signs.

with or without 3 signs = hayz.

If a zatu 'I-'adah woman sees blood for three days and then it stops for some days and again it comes for three more days - then both flows of blood and the pause between them will be considered hayz only if (a) the total days of two flows and the pause between them is not more than ten, and (b) all these days are in the fixed time and fixed number of days of the woman's menses.

if total of 2 flows & the pause is ten or less + all these days are in the fixed time = hayz.

In the following three cases also, the two flows of blood and the pause between them will be counted as hayz:

i. If one of the flows started a day or two before the fixed time.

both flows and the pause = hayz.

ii. If both flows started outside the fixed time but both had the three signs of menstrual flow.

with 3 signs - hayz.
without 3 signs = istihazah.

iii. If one flow (which started outside the fixed time) had the three signs while the other flow started in the fixed time.

with 3 signs = hayz.
without 3 signs = istihazah.

But if one flow or both did not have the three signs of menstruation and none of them occured in the fixed time, then the flow with the three signs is menstrua­tion and without them is istihazah.

If the total days of both flows is more than ten and the pause between them is less than ten days, then the following procedure is to be followed:

i. If one of the flows was in the fixed time without the other, the one within the fixed time will be considered hayz and the other one istihazah.

ii. In the case where none of the flows occurred in the fixed time, then

(a) if one had the three signs but not the other - the one with the signs will be hayz and the other istihazah.

(b) if both flows had the three signs, then the first will be considered hayz and the other will be considered istihazah.

If the pause between the two flows of blood was ten days or more, then in the following two cases they will be considered two separate menstruations:

i. if both flows had the three signs:

with 3 signs = two separate hayz.
without 3 signs = two separate istihazah.

ii. if one was in the fixed time, while the other had the three signs.

If these blood flows occured outside the fixed time and without the three signs, then both will be counted as istihazah.

If the blood stops before ten days and the woman is uncertain whether or not it has stopped completely, then she should examine herself by inserting a piece of cotton inside her vagina and leave it there for a while. Then she should take it out gently - if the cotton comes out dry, she should consider herself pure and perform ghuslu 'I-hayz (unless the pause during menstrual flow is normal in her case).

While examining oneself, it is better "to stand upright leaning on a wall, etc, and lift up one leg and then insert the cotton into the vagina." 8

If such a woman (who is uncertain whether or not her period has stopped completely) does not examine herself and performs ghuslu 'I-hayz, then her ghusl is valid only if the menstrual flow does not start again.

And if she is unable to examine herself, then she should consider herself ha'iz until she is sure of her purity.

But if the cotton comes out stained with blood, the rules differ slightly for the different categories of ha'iz:

If a mubtadi'ah, a muztaribah and a zatu 'l-adah who has her periods for 10 days examine themselves and find that the cotton is stained, then they should consider themselves as ha’iz up to ten days or until the blood stops.

If a woman who has her periods regularly for less than ten days examines herself during her fixed numbers of days and finds the cotton stained, then she should consider herself ha'iz. If the same woman examines herself outside her fixed numbers of days and finds the cotton stained, she should consider herself as ha'iz for up to ten days or until she finds herself pure.

If a zatu 'l-'adah woman of group (c) sees blood for more than ten days, then she should consider her fix­ed number of days as menstruation (even if it is without the three signs); and the remaining days should be con­sidered as istihazah(even if it is with the three signs).

But if both flows can be counted as one hayz, then she should do so. For example, she saw her first flow according to her pattern for three days, then blood stop­ped for four days and started again (with the three signs) for three days (making a total of ten days) and then con­tinued (without the three signs) afterwards - then she would count the first flow + intervening pause + se­cond flow of three days (with the signs) as hayz and the remaining period as istihazah.

first flow + pause + second flow with 3 signs = 1 hayz. later part of 2nd flow without 3 signs = istihazah.

Notes :

8. As explained by imam as-Sadiq. See al-'Amili, op. cit., vol. 2, p. 562.

Adopted from the book : "The Ritual Ablutions for Women (Taharatu N-Nisa')" by : "Sayyid Muhammad Rizvi"