A person who due to some reason, for example: incontinence or bleeding continuously remains in the state of impurity, being unable to remain in the state of purity long enough to perform Salaah is called a Ma’zoor.
One will become a Ma’zoor only if the state of impurity lasts for one complete duration of a Salah time. If throughout this time, blood, urine or any other impurities flowed or dripped continuously, not enabling one to make wudhu and perform the Fardh Salah with purity, then one will be known as a Ma’zoor. The time will be counted from the Salah time immediately following the Salah time in which the illness etc. occurred.
During this time if the illness stopped long enough to enable one to make the faraaidh of wudhu (face, arms etc…) and just the Fardh Salah, then one will not be considered a Ma’zoor.
After qualifying as a Ma’zoor, one will remain a Ma’zoor as long as the bleeding, discharge etc. does not stop for one full Salah time.
Upon becoming a Ma’zoor, it is not necessary for the bleeding, etc. to be continuous in the succeeding Salah times; it will suffice if the bleeding, etc. was for just a moment for one to be continued to be considered a Ma’zoor.
A Ma’zoor shall make Wudhu for every Fardh Salah. The wudhu of a Ma’zoor remains valid for the duration of the Salah time and all the factors which break wudhu besides the factor responsible for making one Ma’zoor, will nullify the wudhu of a Ma’zoor. (Ahsanul Fatawa p.77 v.2 & Fatawa Darul Uloom Deoband p.298 v.1)