Hi, i'm currently on mirena for 3 1/2 yrs now, my period is stable every 3 to 4 weeks but never late, now i'm almost 3 weeks late with one positive pregnancy test when i was 10 days late and a negative blood test(1.2 beta hcg ), internal ultrasound not sh

Rare failure possibl: Can you feel your string? Are you sure it's still there and hopefully in the correct location? It is very very unusual for someone to get pregnant with the IUD in place, but it does occur. And while an ectopic pregnancy is prevented by the IUD, if someone becomes pregnant with an IUD in their uterus, it increases the risk of ectopic pregnancy. Please get follow up this week. And best of luck

It is possible that: you were pregnant and now you are not. A quanitative HCG test should be able to give you an exact answer. You might need to have it done more than once. Remember every method of birth control has a failure rate of some type, but the Mirena (levonorgestrel) is has a very very low failure rate, but it is not zero