Is it permissible for a person afflicted with a fistula, who performs ablution for every prayer, to perform ablution for 'Umrah before the prayer time begins, especially given the presence of an infant and the difficulty in catching congregational prayer at Al-Masjid Al-Haram?

Pus and blood discharged from a fistula must be washed off, and a cloth should be tied over it. These do not invalidate ablution as long as they do not issue from the private parts. As for the discharge of feces, it invalidates ablution in all cases, whether it issues from the anus or from another orifice as long as it is below the stomach. Whatever exits from inside the vagina invalidates ablution. If its discharge is continuous, then its ruling is like that of a person with incontinence: one performs ablution for each prayer after its time has begun. It is permissible to adopt the Maliki school's view that continuous discharge does not invalidate ablution, when there is a need.