I believe its for cervical cancer, gonorrhea, & chlamydia. Herpes Im pretty sure has to be a blood test or a swab of the actual sore... I could be wrong.
I know Chlamydia for starters, but I think Gonorrhea and Herpes is another they can check. I could be wrong on the other two std's, but that's how they checked for Chlamydia on me when I got pregnant, it's protocol during the first tri-mester.