D&C but no miscarriage?

jpb
So I have a lot of questions and figured I'd throw this out to you ladies! 
I've never been pregnant... No miscarriages... nothing. I went in to my doc today and she did an ultrasound. Said I had a slight case of PCOS and a thick uterine lining. AF will be here in about a week so she thinks that may be why it's so thick and wants me to come in after my cycle is finished for another ultrasound. If it's still thick she wants to schedule a D&C.... 
I've only heard of this being scheduled for after a miscarriage? Am I wrong? Anyone had one before that didn't have any history of a miscarriage? Just confused - any help is appreciated!!! I'm only about 8DPO I think.