Can being on your period affect your pap smear results?

Better to delay: Using the current methods for pap preparation, most of the debris is removed, however, it would be preferable to delay the pap while there is active bleeding.

Yes: If the period is somewhat heavy, the blood can interfere with the ability to read the pap smear well, and may need to be repeated. With the newer liquid based smears, this is less likely to be a problem.