What are all the possible reasons for abnormal pap?

Too long: This requires a longer answer than there is room for here. The significant changes on pap smears are mainly due to hpv virus. Depending on the pap smear abnormality you can be observed for a number of years or, if more serious, be treated right away. Most early hpv caused pap abnormalities return to normal within a few years. You still need to be followed closely though.