I had to have that done.
They said my pap smear came back abnormal, it turns out I have cancerous tissue in my cervix that may go away when I have my baby, or I may have to get it cut out after I give birth.
What they do is, they'll rub the inside of your vagina with vinegar, the abnormal cells turn white when this is done. (you could have invasive cancer)
they will then clip a piece of your vagina off to test it, it doesnt hurt that much, but it does hurt. It makes you bleed for about a week, but it will go away.
It's quite far away from your baby when the procedure is done, so nothing should harm the baby. I have to have it done at 30 weeks again to make sure it hasnt spread. Because if it does I might loose my baby.
If ya have any questions send me a msg.