Fatima bint Abi Hubaish came to the Prophet ﷺ and said, "O Messenger of Allah ﷺ I get persistent bleeding from the uterus and do not become clean. Shall I give up my prayers?" Messenger of Allah ﷺ replied, "No, because it is from a blood vessel and not the menses. So when your real menses begins give up your prayers and when it has finished wash off the blood (take a bath) and offer your prayers." Hisham (the sub narrator) narrated that his father had also said, (the Prophet ﷺ told her): "Perform ablution for every prayer till the time of the next period comes."  

جَاءَتْ فَاطِمَةُ ابْنَةُ أَبِي حُبَيْشٍ إِلَى النَّبِيِّ ﷺ فَقَالَتْ يَا رَسُولَ اللَّهِ إِنِّي امْرَأَةٌ أُسْتَحَاضُ فَلاَ أَطْهُرُ أَفَأَدَعُ الصَّلاَةَ فَقَالَ رَسُولُ اللَّهِ ﷺ لاَ إِنَّمَا ذَلِكِ عِرْقٌ وَلَيْسَ بِحَيْضٍ فَإِذَا أَقْبَلَتْ حَيْضَتُكِ فَدَعِي الصَّلاَةَ وَإِذَا أَدْبَرَتْ فَاغْسِلِي عَنْكِ الدَّمَ ثُمَّ صَلِّي قَالَ وَقَالَ أَبِي ثُمَّ تَوَضَّئِي لِكُلِّ صَلاَةٍ حَتَّى يَجِيءَ ذَلِكَ الْوَقْتُ  

(the wife of the Prophet) Um Habiba got bleeding in between the periods for seven years. She asked Messenger of Allah ﷺ about it. He ordered her to take a bath (after the termination of actual periods) and added that it was (from) a blood vessel. So she used to take a bath for every prayer.  

عَنْ عَائِشَةَ زَوْجِ النَّبِيِّ ﷺ أَنَّ أُمَّ حَبِيبَةَ اسْتُحِيضَتْ سَبْعَ سِنِينَ فَسَأَلَتْ رَسُولَ اللَّهِ ﷺ عَنْ ذَلِكَ فَأَمَرَهَا أَنْ تَغْتَسِلَ فَقَالَ هَذَا عِرْقٌ فَكَانَتْ تَغْتَسِلُ لِكُلِّ صَلاَةٍ