I would like to know the conditions of istijmâr in the four schools of fiqh.

Particularly, I have read that in the maliki madhab, it is compulsory for women to do istinjâ after urinating because generally her urine goes beyond its place of exit. What about it in the other madhabs?

Praise
be to Allah

The four madhhabs are agreed that if what is emitted goes
beyond its place of exit and spreads to a large extent, then cleaning
oneself with pebbles (istijmaar) is not sufficient; rather it is essential
to wash the area. 

The reason for that is that istijmaar is a concession that
was granted because of a widespread practice, so it should be limited to
regular situations [when the impurity does not spread]. Anything beyond that
[when the impurity spreads] remains subject to the original ruling, which is
that the impurity must be removed by washing. End quote. 


Al-Mawsoo‘ah al-Fiqhiyyah
(4/121) 

It is acceptable for a woman to clean herself with pebbles
after defecating, according to scholarly consensus. This is clear. 

But with regard to urination: 

According to the Maalikis, cleaning with pebbles is not
acceptable following urination in the case of a woman, whether she is a
virgin or otherwise. They said: That is because the urine usually goes
beyond the place of exit. 

According to the Shaafa‘is, following urination in the case
of a woman – if she is a virgin – whatever removes the impurity itself is
acceptable, whether it is a piece of cloth or anything else. But in the case
of a non-virgin, if the urine reaches the outside of the vagina, as is
usually the case, then cleaning with pebbles is not sufficient, but
otherwise it is sufficient. 

It is mustahabb to wash the area in that case. 

Among the Hanbalis, there are two views concerning the
non-virgin: 

1.    

that istijmaar is acceptable

2.    

that the area must be washed. End quote.


Al-Majmoo‘ah al-Fiqhiyyah
(4.122) 

See also: Mawaahib al-Jaleel by al-Hattaab (1/284);
Minah al-Jaleel by ‘Ulaysh (1/105) 

Ibn Qudaamah (may Allah have mercy on him) said: 

A virgin woman is like a man, because the hymen prevents the
spread of urine. 

But in the case of the non-virgin, if urine is emitted in a
stream and does not spread, then the same applies. 

But if it spreads to the site of menstruation, in that case
our companions said that it must be washed, because the site of menstruation
and childbirth is different from the place where urine exits. 

It may be that washing is not required, because this is usual
in her case, therefore istijmaar is sufficient. Moreover, if washing were
required, when this happens to many women, the Prophet (blessings and peace
of Allah be upon him) would have explained that to his wives, because it is
something that they would have needed to know.

End quote from al-Mughni (1/118) 

The correct view is that with regard to this matter, a woman
is like a man, whether she is a virgin or otherwise. 

This is the view favoured by a number of well-versed
scholars, such as al-Majd Ibn Taymiyah, the grandfather of Shaykh al-Islam
Ibn Taymiyah, and al-Mardaawi. See: al-Insaaf (1/160) 

Shaykh ‘Abdullah at-Tayyaar was asked: 

It is said that it is stipulated that a woman should clean
herself with water (istinja) after urinating, and this is said by those who
claim to belong to the Maaliki madhhab. Is this view correct? 

He replied: 

I do not know of the basis for that. A woman is like a man:
she may clean herself with water (instinja) or she may clean herself with
pebbles (istijmaar), but if she follows the pebbles with water, that is
better. End quote. 


http://www.m-islam.com/new/s/1276 

For more information, please see the answers to questions no.
9645 and 111813 

And Allah knows best.