What Are The Risks Of Conceiving While Having Mirena IUD?

I have mirena iud and it is expired by a couple years. I want to know the risks that i could become pregnant and also if I can become pregnant what are the risks of becoming pregnant with it still in place. I've had stomach cramping and breast tenderness for about a week. Which i have never experienced except when i have become pregnant before. I do not have health insurance at this time so haven't had it taken out and not sure if the emergency room will remove it