Mirena IUS

Question 1

Mirena IUS: how it works

Answer 1

Mainly by preventing implantation; sometimes by preventing fertilisation

Question 2

Mirena IUS: Duration of use

Answer 2

• 5 years
• Until contraception no longer needed if woman 45 years or more at time of insertion and does not have periods with IUS in place

Question 3

Mirena IUS: Failure rate

Answer 3

• Fewer than 1 in 100 women over 5 years

- Expulsion occurs in fewer than 1 in 20 women in 5 years

Question 4

Mirena IUS: Effects on periods

Answer 4

• Irregular bleeding and spotting common in first 6 months

- Oligomenorrhoea or amenorrhoea likely by end of first year

Question 5

Mirena IUS: Other risks

Answer 5

• Up to 60% of women stop using the IUS within 5 years for unacceptable vaginal bleeding and pain, less common reason is hormonal (non‑bleeding) problems
• Ectopic pregnancy: overall rates lower than with no contraception But if a woman becomes pregnant with IUS in situ, risk is about 1 in 20 so she should seek advice to exclude it
• Pelvic inflammatory disease: less than 1% for women at low risk of STI
• Uterine perforation: less than 1 in 1000
• Change in mood or libido: may be a small effect, similar for IUD and IUS
• Acne: risk may be increased, but is an uncommon reason for stopping use
• No evidence of effect on: Weight gain

Question 6

Mirena IUS: Return to fertility

Answer 6

No delay in return of fertility

Question 7

Mirena IUS: Advice at time of fitting

Answer 7

• There may be pain and discomfort for a few hours and light bleeding for a few days
• Watch for symptoms of uterine perforation
• Follow‑up visit after first menses or 3–6 weeks after insertion
• Return at any time if problems or to change method
• Check for threads regularly

Question 8

Mirena IUS: misconceptions

Answer 8

• There is no evidence that the effectiveness of the IUS is reduced when taking any other medication
• IUS use is not contraindicated in women with diabetes
• IUS is a safe and effective method of contraception for women who are HIV positive or have AIDS (safer sex using condoms should be encouraged in this group)
• All progestogen‑only methods, including the IUS, may be used by women who have migraine with or without aura
• Women with a history of VTE may use the IUS
• IUS is medically safe for women to use if oestrogen is contraindicated.

Question 9

Mirena IUS: timing of fittings

Answer 9

• At any time during the menstrual cycle (but if the woman is amenorrhoeic or it has been more than 5 days since menstrual bleeding started, additional barrier contraception should be used for the first 7 days after insertion)
• Immediately after first‑ or second‑trimester abortion or at any time thereafter
• From 4 weeks post‑partum, irrespective of the mode of delivery