Praise be to Allah.
With regard to blood that comes out from anywhere other than the front and back passage, there is a difference of opinion among the fuqaha’ as to whether it invalidates wudoo’ or not. We have discussed this previously in the answer to question no. 45666. The most correct view is that it does not invalidate wudoo’; this is the view of Imam Maalik and Imam ash-Shaafa‘i (may Allah have mercy on them both) and it is the view favoured by Shaykh al-Islam Ibn Taymiyah.
With regard to what gets onto your garment of blood or pus, if it is a small amount, there is nothing wrong with you praying in that garment. If it is a large amount, then you have to wash it or change your garment, according to the majority of fuqaha’.
Some scholars are of the view that blood that comes out of a person’s body from anywhere other than the front and back passages is taahir (pure) and not najis (impure).
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: The view of those who say that human blood is taahir is a very strong view, because the texts and analogy indicate that.
End quote from ash-Sharh al-Mumti‘ (1/443).