For my current employer they required a full physical - they did visual (eyesight test), color recognition, bend and squat, blood pressure, piss test, but never took blood.

And I work in the pharmaceutical industry - if that's any indication. Maybe with security companies, banks, something like that they might go for blood?

One thing to remember though if they say you need a pre-employment physical - you won't have anywhere to store a substitute bag or other container.... they'll have you in your skivies.