• The levonorgestrel intrauterine system (IUS) is a small polyethylene T-shaped frame with a reservoir around the vertical stem that slowly releases levonorgestrel into the uterus.
• One levonorgestrel-releasing IUS is licensed in the UK; it is marketed as the Mirena^® IUS.

In depth

• There is no evidence that the levonorgestrel-releasing intrauterine system causes weight gain.

In depth

• Enquire about the user's preferences and any concerns about using the levonorgestrel intrauterine system (IUS).
• In young women and women with special needs, assess their competence to decide, and support them in making their own decisions about contraception.
• Exclude pregnancy.
• Check the UK Medical Eligibility Criteria to ensure that the woman is eligible for insertion of the levonorgestrel IUS.
• Assess the risk for sexually transmitted infection and, when appropriate, advise testing, promote safer sex, and/or refer for counselling (also consider each time the IUS is reinserted). If testing for sexually transmitted infections is requested, do this before inserting the device.

In depth

• Starting the levonorgestrel-releasing intrauterine system (IUS):
• Ideally insert the device in the first 7 days after the onset of menstruation.
• Additional contraceptive protection will not be required.
• However, if this is not possible:
• Insert the device at any other time in the menstrual cycle provided that it is reasonably certain that a woman is not pregnant. This is an unlicensed use. Advise barrier contraception (such as condoms) for the next 7 days.
• Alternatively, use a hormonal method in the interim, so the fitting can be scheduled for any mutually convenient time.
• If there is a delay before the IUS can be fitted, combined hormonal contraception (pill, patch, or vaginal ring [not suitable post-partum if the woman is breastfeeding]), the progestogen-only pill, or the progestogen-only injectable can be used as a bridging method.
• Replacing the device:
• Insert at any time of the menstrual cycle.

In depth

• If uterine perforation at insertion is suspected, the procedure should be stopped and vital signs and the level of discomfort monitored until stable.
• Uterine perforation should also be considered if a woman returns within the first few days of insertion complaining of marked pain (which may only be intermittent), and the threads cannot be located.
• Urgent and specific follow-up should be arranged to include ultrasound scan and/or plain abdominal X-ray to locate the device if it has been left in situ.

In depth

• Follow-up after the first menses, or 3–6 weeks after insertion, to exclude infection, perforation or expulsion.
• Advise the woman to return at any time if she wants to discuss problems, if she wants to change her method of contraception, or if it is time to have the IUS removed or changed.

In depth