The levonorgestrel intrauterine system is used for contraception and in the treatment of heavy menstrual bleeding. It is a small T-shaped piece of plastic that is placed in the uterus. Once there it releases levonorgestrel, a progesterone, which acts locally to prevent pregnancy. It is usually replaced every five years.
The contraceptive action of the levonorgestrel intrauterine system works in a number of ways. Firstly, it causes thickening of the cervical mucus, making it difficult for sperm to enter the uterus, or womb, from the vagina. Secondly, it alters the endometrium and minimizes thickening of the lining and therefore shedding, which decreases menstrual bleeding and prevents implantation of any fertilized egg. Thirdly, in some women, insertion of a levonorgestrel intrauterine system prevents ovulation, or the release of the egg.
While the levonorgestrel intrauterine system is similar to the traditional copper intrauterine device (IUD), it differs in the fact that it not only works by being in the womb but has the additive effect of the release of levonorgestrel. The choice of contraceptive method should be made in consultation with a doctor or nurse and depends on numerous factors including age, whether or not the woman has had children and other risk factors such as smoking or cancer history.
When the levonorgestrel intrauterine system is inserted, it will be done by a trained doctor or nurse. It is usually inserted during the first seven days of the menstrual cycle and, if done so, will give immediate contraceptive coverage. A pregnancy test should be done before insertion. The levonorgestrel intrauterine system does not protect against sexually transmitted diseases (STDs) and condoms should be used in any situation where STDs could be transmitted.
Adverse effects may occur after insertion. These may include changes in menstrual bleeding, spotting, ovarian cysts, depression and headaches. The system may also become displaced so it is important that placement is checked regularly. The health care professional who inserts the device will train the woman how to do this. Should adverse effects be severe, immediate medical advice should be sought.
It is important that the doctor is informed of any other medications and clinical conditions before the levonorgestrel intrauterine system is inserted. Its use is contraindicated in some conditions, and although rare, some interactions may occur between the levonorgestrel intrauterine system and other medications. This includes complementary, over-the-counter and homeopathic preparations.