The Mirena IUD (Mirena Coil)

Mirena IUD (Mirena coil) is an IntraUterine System (IUS), a hormonal contraceptive device that is placed in the uterus and releases a low dose of levonorgestrel (a progestogen hormone).

Clinical uses:
* Contraception;
* menorrhagia (heavy periods), endometriosis, chronic pelvic pain, dysmenorrhoea, and anaemia;

Fitting
The IUS can only be fitted by a qualified medical practitioner. The device should be inserted according to the manufacturer's instructions using aseptic technique to avoid introduction of bacteria into the uterus. Antibiotics should be given before insertion to women at high risk for endocarditis (inflammation of the membrane lining the heart), but should not be used routinely.

During the placement appointment, the cervix is dilated in order to sound (measure) the uterus and insert the IUS. Cervix dilation is uncomfortable and, for some women, painful. Doctors often advise women to take painkillers before the procedure to reduce pain and discomfort. Insertion may be more comfortable if done midcycle, when the cervix is naturally dilated.

Once in place, the IUS is approved for birth control for up to 5 years. The cumulative 5-year pregnancy rate is estimated to be 0.7%.

Mechanisms of contraception
The Mirena is intended to initially release a daily dose of 20 micrograms levonorgestral (a progestin). It is not known how exactly Mirena works. It has several effects on the reproductive system, which are believed to explain its use to prevent pregnancy.

* Frequency of ovulation is reduced;
* Cervical mucus is changed to obstruct passage of sperm through the cervix;
* The presence of a foreign body in the uterus prompts the release of leukocytes and prostaglandins by the endometrium, substances that are hostile to both sperm and eggs;
* The endometrium is thinned.[8] It has been suggested that this inhibits implantation of embryos, though no experiment has yet confirmed or disproved this theory;

Removal
Generally IUS removal is easiest if undertaken towards the end of a women's period and involves a doctor or trained nurse using a pair of forceps to take hold of the IUS's thread and gently retract.

A "lost coil" occurs when the thread can not be felt by a women on routine checking and is not seen on speculum examination. Various thread collector devices or simple forceps may then be used to try and grasp the device through the cervix. In the rare cases when this is unsuccessful, an ultrasound scan may be arranged to check the position of the coil and exclude its perforation through into the abdominal cavity or its unrecognised previous expulsion. Hysteroscopy is very rarely needed.

After removal of the IUS normal fertility is regained after a few months, with a near normal 80% of women able to conceive within 12 months.

Contraindications
IntraUterine Systems may not be inserted in:
* Women who are pregnant;
* Women with an active STD, or who have had PID within the past three months;
* Women who have sepsis (infection) following childbirth or abortion;
* Women with certain uterine abnormalities;
* Women with pelvic tuberculosis;
* Women with cervical, endometrial, or ovarian cancer awaiting treatment;
* Women with malignant trophoblast disease;

Side effects and complications
Location of device
Following insertion, the IUS may be expelled through the cervix. An expulsion rate of 4% was observed in the manufacturer's clinical trials, with most (3%) occurring in the first year of use. Expulsion is more common in younger women, women who have not had children, and when an IUS is inserted immediately after childbirth or abortion.

A rare but potentially serious complication is that of uterine perforation. This may occur either during the device's insertion, or from its later embedment into the myometrium (uterine wall) and subsequent migration through to the intra-abdominal cavity. Perforation can cause internal scarring, infection, or damage to other organs, and may require surgery. Uterine perforation has been reported at rates ranging from 1 to 2.6 per 1000 insertions. It is believed that perforations are significantly underreported, however, and actual perforation rates are likely higher.

Both expulsion and perforation result in loss of contraceptive cover and the position of the thread of the IUS should be self-checked at least once per menstrual cycle to verify that it is still in place, or, in the absence of menstrual cycles, once per month.

The string(s) may be felt by some men during intercourse. If this is problematic, the provider may tuck the strings behind the cervix, cut the strings shorter, or in more extreme cases cut the strings to level with the cervix. Cutting the strings even with the cervix prevents the woman from checking the device's correct placement, and may complicate removal.

Pelvic inflammatory disease and STDs
Pelvic inflammatory disease (PID) is caused by certain sexually transmitted diseases (STDs). PID is a serious condition that may result in infertility. In women who have STDs, an IUD will increase the risk of PID. Therefore, IUDs are not recommended for women at high risk of STDs.

Women who have more than one sexual partner, or whose partners have more than one sexual partner, are at increased risk for STDs. Younger women are statistically at higher risk for STDs.

An animal study suggested that progestin-only hormonal contraceptives such as Mirena might increase the risk of HIV transmission, because of the thinning of the vaginal walls caused by these methods. However, a number of studies of human populations showed that progestin contraceptive use does not increase the risk of acquiring HIV.

However, like the Pill and other non-barrier forms of contraception, the IUS offers no protection against sexually transmitted disease.

Postpartum and post-abortion insertion
An IUS may be inserted immediately postpartum (within 48 hours). With insertions after 48 hours, perforation of the uterus is more likely to occur when uterine involution is incomplete; involution usually completes by 4-6 weeks postpartum. Special considerations apply to women who plan to breastfeed.

Also to allow for uterine involution, insertion of an IUS is not recommended for women who have had a D&E termination (second-trimester abortion) within the past four weeks.

To reduce the risk of infection, insertion of an IUS is not recommended for women who have had a medical abortion but have not yet had an ultrasound to confirm that the abortion was complete, or who have not yet had their first menstruation following the chemical abortion.

Expulsion is more common when an IUS is inserted immediately after childbirth or abortion.