Intrauterine contraceptive devices

Intrauterine contraceptive devices comprise both conventional copper intrauterine devices (IUDs) and levonorgestrel-releasing intrauterine systems (IUS, Mirena). The IUS is also used in the management of menorrhagia

Effectiveness

• both the IUD and IUS are more than 99% effective

Mode of action

• IUD: primary mode of action is prevention of fertilisation by causing decreased sperm motility and survival (possibly an effect of copper ions)
• IUS: levonorgestrel prevents endometrial proliferation and causes cervical mucous thickening

Counselling

• IUD
  • can be relied upon immediately following insertion
  • the majority of IUDs with copper on the stem only are effective for 5 years, whereas some of the IUDs that have copper on the stem and the arms of the T may be effective for up to 10 years
• IUS
  • can be relied upon after 7 days
  • the most common IUS (i.e. Mirena - levonorgestrel 20 mcg/24 hrs) is effective for 8 years, but if used in women ≥45 years it is effective until 55 years
  • if used as endometrial protection for women taking oestrogen-only hormone replacement therapy they are only licensed for 5 years

Potential problems

• IUDs make periods heavier, longer and more painful
• the IUS is associated with initial frequent uterine bleeding and spotting. Later women typically have intermittent light menses with less dysmenorrhoea and some women become amenorrhoeic
• uterine perforation: up to 2 per 1000 insertions and higher in breastfeeding women
• the proportion of pregnancies that are ectopic is increased but the absolute number of ectopic pregnancies is reduced, compared to a woman not using contraception
• infection: there is a small increased risk of pelvic inflammatory disease in the first 20 days after insertion but after this period the risk returns to that of a standard population
• expulsion: risk is around 1 in 20, and is most likely to occur in the first 3 months

New IUS systems

The Jaydess= IUS is licensed for 3 years. It has a smaller frame, narrower inserter tube and less levonorgestrel (LNG) than the Mirena coil (13.5 mg compared to 52 mg). This results in lower serum levels of LNG.

The Kyleena IUS has 19.5mg LNG and is also smaller than the Mirena but is licensed for 5 years. It also results in lower serum levels of LNG. The rate of amenorrhoea is less with Kyleena compared to Mirena.