Hello Thanks for writing to us with your health concern. As such, chances of pregnancy are very less with Mirena. however, the offside is that if a pregnancy DOES occur, then chances of an ectopic pregnancy are much higher than normal conceptions. Have you missed your period? Or had abnormal spotting or bleeding ? Apart from pain and fainting attacks, you should have had some abnormal vaginal bleeding. An ectopic pregnancy will be easily picked up by a blood pregnancy test. Diverticulitis would not cause you to pass out. It could be a twisted ovarian cyst, or pancreatitis also. Please have an abdominal and pelvic ultrasound with a blood pregnancy test. all the best.