Mirena is a small T-shaped hormone-releasing intrauterine device (IUD). It releases a small amount of levonorgestrel every day, a type of progestin. It can be inserted for contraception, to decrease heavy period, for treatment of endometriosis or endometrial hyperplasia. Once it is inserted, it can be left inside the uterus for 7 years and 5 years for contraception or for treating heavy menstrual bleeding respectively.
The insertion procedure is a simple clinic procedure. It is performed preferably in the first 7 days of the woman’s period, when she is not pregnant, not having active pelvic infection or unexplained abnormal vaginal bleeding. Sometimes Mirena can be inserted immediately after an operation in the operating theatre, for example, after hysteroscopy or surgical termination of pregnancy.
The insertion procedure is well-tolerated even when it is done in the clinic without anaesthesia. The woman might experience some lower abdominal cramps, pain and light vaginal bleeding. Serious complications are rare. These include uterine perforation (around 0.2%) and pelvic infection (around 0.5%). The risk of expulsion of the IUD is about 1 in 20 and is most common in the first year, especially within the first three months after insertion. Therefore, the woman should have a follow-up appointment to check the position of the IUD around 2-3 months after insertion. Irregular, light, prolonged vaginal bleeding is common after Mirena insertion but tends to improve with time. Mirena can decrease menstrual bleeding after 3 months of use. Around 20% of women stop having periods one year after Mirena insertion.
If a woman wants to get pregnant, she can start trying immediately after removing Mirena. There is no delay in return of fertility after removal. Mirena can be removed in the clinic by gently pulling onto the thread attached to the end of the IUD. Occasionally, the IUD may get stuck or the thread is broken, then the removal becomes more complicated, requiring anaesthesia. Immediate replacement of a new Mirena can be done after removal of the old one, if necessary.