Hi. I Got Mirena Coil 5 Years Now And Went

Hi. I got Mirena coil 5 years now and went 20 days ago to a procedure for replacement. As the precedure was under GA I had urine and blood test done and had positive test for pregnancy. Re checked blood test in 14 days again is positive - same result 5.0 UI/ml. I m not feeling in any way pregnant and last my contact was about 6.12.2015. The consultant still refuse to go ahead with the procedure and ask me to do another blood test in 4 weeks. I am so confused about. What can cause thsi border line result please