Mirena IUD The Mirena Intrauterine Device is a small, plastic T-shaped device that is inserted into the uterus. It uses topical delivery of progestin to the uterine cavity to prevent pregnancy. The Mirena also helps control heavy, painful cycles. It can remain in place for up to five years, but can be removed earlier with a quick return to fertility.  Side effects include altered bleeding patterns for several months, cramping with insertion, IUD expulsion, and a small risk of uterine perforation upon insertion. The Mirena is available to all women, regardless of pregnancy history. You should not get an IUD if you have cervical or uterine cancer, pelvic inflammatory disease, or a distorted uterine cavity.