Signs and characteristics of menstrual blood?

Question : Generally, women are more knowledgeable than men regarding the rulings

Answer : of menstruation. A woman knows her menstruation by its color, its warmth, its thinness, and also by its smell and its symptoms, such as pain. There is a fifth sign, which is that some contemporary doctors have said that menstrual blood does not clot, whereas other blood does. If menstrual blood falls on a garment, for example, it remains unclotted because it has already clotted in the womb and does not clot a second time. However, if it clots on the garment, this is evidence that it is not menstrual blood, but rather istihadah (irregular non-menstrual bleeding) or something similar. This woman who experienced a three-day period says that in the first month she saw purity, and then eight days came to her. We say that, according to the stronger position, there is no limit to the period of purity. The interval between two periods may be twenty days, or more, or less. We have even heard that some women have a purity period of three months and a full month of menstruation.
Allah is capable of all things. It is as if the menstruation gathers at one time to compensate for all that preceded it: three months without menstruation and a full month of menstruation. The important thing is to say to this woman that the second period may be a valid menstruation, because the stronger position is that there is no minimum limit to the period of purity between two periods. Therefore, she does not fast and does not pray.