It sounds like your sister's friend got a perforated uterus from her IUD. That can happen, as far as I know, due to a bad insertion or a small uterus. I have friends who have IUDs and have never had kids and they are fine. The other option you might consider is Implanon. It's a little device that get inserted in your arm. A friend of mine had hers for a few years to help control her endometriosis.