It's just a decal, if you are on PC - it can be easily replaced or removed altogether.
If you are on a console, well... Either don't play or stop being afraid of blood, no other way around it.
I know I can mod it out, but as I said, console users can't. I find it hard to believe that I'm the only person who is annoyed by the blood... Its not gonna stop people from playing obviously, but if you get splatter of blood on your eyes, its going to make you almost completely blind until you blink. No blood screen is better :] Think about how small your pupil is.