Hello,
You can get pregnant with Mirena. Hence to confirm the status of pregnancy, I suggest you to test for pregnancy by a highly sensitive pregnancy test 10 days post ovulation with a sensitive ( 20 - 25 mIU ) pregnancy test. Also then I would suggest you to get your serum HCG levels estimated since this is more specific than urine for pregnancy tests. Presence of IUD will not effect the pregnancy test.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing
i had it for over 2 yrs and never got pregnant but once i had it removed it took me a few months to get pregnant again but as far as it affecting the test u would have to call and ask your doc b/c i do know it could be life threating to get pg while having it