Had a pap smear on day 10 of menstration. Pap came back normal but shows endometrial cells on uterine lining. What does this mean? Going for a biopsy.

Likely okay. Typically, unless a woman is having irregular bleeding, endometrial cells on a pap aren't worrisome at all. That's based on a new recommendation for pap smear management. If you have irregular or heavy bleeding, doctor will want to rule out pre-cancer as cause, hence, biopsy of uterine lining. No harm in biopsy. Your doctor knows you best, so be sure to ask him/her why they have concerns for biops.