I just wanted to chime in here and share my Mirena insertion story. I have a hereditary condition called a tipped / tilted / retroverted uterus. (See definition: http://www.inletmedical.org/tipped_uterus.asp)
It can be traced back as far as my great-grandmother, and up to 20% of women have it. I was aware of my condition before I had my Mirena inserted but failed to mention it to my gynecologist. I didn't think of it beforehand! My doctor had a very difficult time placing the device because of the 90 degree angle of my uterus. First, he had to use a very small tube to thread through my cervix. He kept "hitting a wall". So he dilated my cervix and gave it a very hard push. Well, after 20 minutes and a little screaming, the IUD was finally in. But I had a strong vasovagal response to the cervical dilation and SEVERE pain, and I passed out on the table, spread-eagle mind you! I was revived with a shot of Atropine, and I came around after eating sugar. I've had the IUD for 7 months and just have the typical discomforts from time to time. I AM concerned about having it removed and don't want a repeat of my experience with the insertion. I might ask for an ultrasound beforehand to determine the placement and orientation of my uterus.
THE TAKE-HOME MESSAGE IS TO INFORM YOUR DOCTOR IF YOU HAVE A TIPPED UTERUS BEFORE YOU HAVE AN IUD INSERTED.