The blood which is not haidh or nifas is called istihadha. lstihadha has been divided into 3 categories:
If the blood does not penetrate the cotton-pad used for protection, it is called "istihadha qalila" (minor istihadha).
There is no ghusl for this category of istihadha; but she must do wudhu for every prayer. She is not allowed to pray two prayers with one wudhu.
If the blood penetrates the cotton-pad but does not exceed it, it is called "istihadha mutawassita" (medium istihadha).
She should do one wudhu for every prayer and one ghusl daily. For example, if she had seen this istihadha before Zuhr, she should do ghusl before Zuhr and should pray Zuhr with that ghusl and one wudhu as mentioned earlier. The 4 later prayers (up till the morning prayer of the next day) should be prayed with one wudhu each.
If the blood exceeds the cotton-pad after soaking it, it is called istihadha kathira (major istihadha). She should do separate wudhu for each prayer, as mentioned earlier, and should do 3 ghusls daily: One for morning prayer, one for Zuhr and Asr and one for Maghrib and Isha. She should pray Zuhr and Asr together and Maghrib and Isha together.
Note: In all cases it is emphasized that she should change the cotton-pad before every wudhu.
2. If she is unable for any reason (described in lesson 48) to do ghusl or wudhu, she should do tayammum in place of that ghusl or wudhu.
3. If a woman observes the rules mentioned above, she should not think herself as najis; she will be clean.