Your doctor will inform you of this. For sure, they'll probably analyse your sperm to see if they're viable, and they'll get a sperm count to see if there are enough (a high sperm count is good, because it ups the chances of pregnancy).

I'm not sure what blood tests they'll ask for, though.

What you need a test for? STD's? Sperm count test are performed when there is a infertility situation and they are looking for a reason as to what could be the cause.