look what happened to Sami when she got trapped in the elevator! You can’t be too careful about those evil things.
Seriously, I believe (not 100% sure about this one) that there are signs that show up in a routine CBC blood test that indicate a woman may be pregnant. If those are seen, a regular pregnancy test is done. I’ve seen it happen on the medical reality shows where someone has come in for some kind of trauma and they discover she is PG after the blood work comes back.