Blood on clothes
In the name of Allah, the most Beneficent, the most Merciful.
If the blood is such that if left alone it would not have flowed (within that sitting) then the wudhu will not break irrespective of whether traces of blood can be seen on ones clothes or not. (Ahsanul Fatawa p.28 v.2)
Only Allah Knows Best
Mohammed Tosir Miah
Darul Ifta Birmingham.