Description
Levonorgestrel containing IUDs are available in more than 50 countries for over 10 years. Approximately 2 million women have used Levonorgestrel containing IUDs. In December 2000, the US Food and Drug Administration approved a Levonorgestrel Intrauterine
System manufactured by Berlex Inc. and marketed as Mirena.
How It Works
The levonorgestrel Intrauterine System is a T-shaped polyethylene device. The frame is 32 millimeter in both the horizontal and the vertical directions. The cylindrical reservoir around the vertical stem contains a mixture of silicone and 52 mg of levonorgestrel, a progestin widely used in implants, oral contraceptives, and vaginal rings. 25 microgram of levonorgestrel is released every day. A monofilament removal thread is attached to a loop at the end of the vertical stem. Mirena is packaged within a newly designed inserter, which is discarded after use. Mirena has
an effective life of 5 years. Like other copper bearing IUDs, Mirena can be inserted within the first seven days of onset of menstruation.
Advantages and Precautions
With few exceptions, the mechanism of action, indications, precautions, side effects and complication, and time of insertion are same as copper IUDs.
Mirena has many advantages over the copper IUDs. It is highly effective with the first year failure rate of 0.1 percent and five year cumulative failure rate of 0.7 percent. There is a marked reduction in menstrual blood loss and the systemic level of hormone is very low as compared to the other progesterone only methods. Unlike copper IUDs, Mirena provides dramatic relief in dysmenorrhea.
Once inserted it is effective for 5 years and fertility returns rapidly on discontinuation. Eighty percent of the women intending to get pregnant will become pregnant within 12 months of discontinuing Mirena. This is comparable with pregnancy rates following discontinuation of other barrier contraceptive methods.
Mirena has many noncontraceptive benefits. It has beneficial effect on menorrhagia, dysmenorrhea and reduces the risk of pelvic inflammatory disease. It also reduces the risk of endometrial cancer by 50%.
Unlike copper IUDs Mirena contains levonorgestrel and so the women having active liver disease, liver tumor, known or suspected carcinoma of the breast or genital actinomycosis should not use Mirena. Women with diabetes and using Mirena should monitor their blood glucose level more regularly.
Expulsion rates for Mirena are little higher than copper IUDs. The ovarian cysts are three times more common in Mirena users. 1.2 percent of Mirena users develop ovarian cysts as compared to 0.4 percent of non users. As with copper IUDs early spotting, particularly during the first three months could be disturbing to many women. Up to 20 percent of women develop amenorrhea by the end of the first year of use and may not be acceptable to many women.
In a study conducted by WHO of over 22000 women found that the risk of pelvic infection is higher during first 20 days of Mirena insertion. The risk of infection following insertion of Mirena can be reduced, by proper screening of the client and following proper infection prevention measures at the time of insertion.
LNG IUS should be removed if woman develops migraine or focal neurological conditions, severe headaches, jaundice, increased blood pressure, stroke or myocardial infarction.
