IUS ‘Mirena’ coil– levanogestrel coated coil (NB the dose in the coil is much lower than that of the PoP
Mechanism of action
- All IUCDs are though to have some action as a foreign body, stimulating leukocytes and prostoglandin release by the endometrium, which possibly provide a contraceptive effect
- Progestogenic effects:
- Thickening of the cervical mucus
- thinning of the endometrium
- (in some women) inhibition of ovulation
Pros and Cons
- Pros
- >99% effective
- Can last long term (commonly 5 years but can be much longer)
- Dual license for treatment of menorrhagia (reduces pain/flow)
- High rate of amenorrhea
- Can be used also as the progestogenic component of HRT (for up to 4 years)
- Fully reversible
- Cons
- Requires specialist fitting
- Early on, may cause irregular bleeding/side effects
- ‘Lost threads’ – expulsion, malposition, perforation
- ? PID
- Ectopic pregnancy risk ?
- ? Difficult to insert in nulliparous women (can be overcome with prostaglandin gel if need be)
Copper Coil
- Lasts 5-10 years
- Few problems or side effects
- Avoids hormone treatments
Mechanism
- Foreign body effect
- Direct toxicity of Cu to sperm
- Less sperm reach the upper genital tract
- Altered uterine/tubal fluid
Pros and Cons
- Pros
- Lasts 5-10 years
- Highly effective (>98%)
- Fully reversible
- Immediately effective
- Also used for emergency contraception (very effective)
- Cons
- Heavy, painful periods
- Irregular bleeding
- Require specialist fitting
- Insertion risks e.g. perforation, infection
- ‘lost threads’
- Risk of ectopic pregnancy
- ? Difficulty to insert in nulliparous women
Contraindications to IUCDs
- Absolute
- Pregnancy
- ? vaginal bleeding
- Acute PID
- Wilson’s disease/ CU allergy *
- Relative
- PHx of ectopic pregnancy *
- Cervical/Vaginal infection
- Fibroids
- Anaemia *
- Menorrhagia *
- Recent history of PID *
- Valvular heart disease *
- ? nulliparity *
- Multiple partners *
- Immunosuppressed (steroids/HIV/immunosuppression) *
* Does not apply to Mirena coil
Infection and the IUCD
- Coils do NOT CAUSE pelvic infection
- Can make pre-existing infection worse
- Highest risk 20 days post insertion- thereafter background risk
- Treat prior to insertion if known