Sheikh Fawzān – may Allāh preserve him – said, “Yes, it breaks one’s wuḍū', because it is impure blood.” The evidence for this is the ḥadīth of Fāṭimah Bint Abī Al Ḥasan in which she was post menstrual but with some blood and Allāh’s Messenger (May Allāh praise him and Peace be upon him) said, «then perform wuḍū` and pray because it is blood from vessels» [Authenticated by Al-Albānī in Ṣaḥīḥ Al Jāmi’ /765].