Does period blood cause inflammatory exudate on pap if you had light period when testing done?

No, menstruation doesn't cause such pap smear changes. Most women with pap results like this have nothing wrong at all, i.e. the cause of the inflammation isn't apparent and usually goes away. If no symptoms like vaginal discharge or vulvar irritation, probably all is OK. STD testing is recommended if you may be at risk. Best to discuss with your doctor. Good luck.

It is best to have it done when not having a period.