I thought you stopped offering OWO?
I don't think there's anything you can catch from blood that you couldn't also catch from semen; obviously it's not pleasant, but your stomach acid is pretty efficient stuff. As ever, if you're worried about stuff like this then the sex you're having isn't as safe as you'd like it to be; your health is your responsibility and it isn't up to punters to fill us in on their medical history.
IME bloody semen/urine can happen for all sorts of reasons and also be completely out of the blue, so if it bothers you that much (and it does me, which is why I don't do OWO, amongst plenty of other reasons) then don't