Mukhtasar Bukhari (Abridged) 171 — Washing off blood is sufficient

Umm al-Mu’minin Aisha Siddiqa (may Allah be pleased with her) says that Fatimah bint Abi Hubaysh came to the Prophet Muhammad (peace be upon him) and said, “O Messenger of Allah! I am a woman who suffers from continuous bleeding (istihada) and therefore do not become pure for many days. Should I stop offering prayers?” The Messenger of Allah (peace be upon him) said, “No! This is blood from a vein and not menstruation. So when your menstrual period comes, stop offering prayers, and when it passes, wash the blood from your body and then offer prayers. Then perform ablution for every prayer until the (menstrual) period returns (then stop offering prayers again).”