Contents
Introduction
The hormonal implant (aka Implanon after a commonly used brand) is a form of contraception that involves placing a rod-shaped device subcutaneously, typically in the skin of the upper arm, which then slowly releases progesterone, providing effective contraception for 3 years.
Advantages
- Efficacy:
- 99.5% effective
- 1 woman in 200 will get pregnant in the course of a year when used as the sole form of contraception
- LARC – long-acting reversible contraception
- LARC methods tend to be more effective (‘set and forget’) than other methods (e.g. pill or condoms)
- Lasts up to 3 years
- Simple procedure to insert and remove with local anaesthetic
- Does not effect bone density (unlike injectable progesterone)
- Quick to reverse when removed
Disadvantages
- Unpredictable bleeding patterns – 20% will have amenorrhoea, 60% have irregular periods, 20% will have frequent or prolonged bleeding – most of these will improve within 3 months. This can be alleviated with:
- Tranexamic acid – 1g/6-8h for up to 5 days – an antifibrinolytic, can reduce menorrhagia by 50%
- Mefanamic acid – 500mg/8h – an NSAID – antiprostaglandin – taken during periods of heavy bleeding, can reduce menorrhagia by 30%. Is also useful for dysmenorrhoea. Contraindicated in peptic ulcer disease
- Other NSAIDs may also be beneficial
- Removal of the implant
- Use of the COCP for 3 months in conjunction with the implant
- Additional training required by practitioner for insertion and removal – can restrict access to the method
- Breast tenderness, headache, mood changes
Efficacy
Quoted as: >99% effective
Described as: over the three year duration of treatment, <0.1% of women will become pregnant
- In obese women, the level of etongestrel (the active ingredient) is reduced during the third year, and there may be a risk of pregnancy –thus replacement or alternative contraception should be sought after 2 years
Mechanism
- Progesterone released slowly
- Prevents ovulation
- Thickens cervical mucous
- Prevents proliferation of the endometrium, making implantation difficult.
Side effects
- Acne
- Breast tenderness
- Mood swings
- Changes in libido
- Infection
- Small risk of local infection at the implant site
- Affect on periods – can make them shorter, longer, heavier or lighter, and the response is unpredictable. If bleeding is particularly heavy or persistent, it can be treated with…
Benefits over oral POP
More likely to inhibit ovulation, thus:
- Less likelyhood of periods
- Recued risk of ovarian cysts and ectopic pregnancy
Also, no interaction with non-enzyme inducing antibacterials
Prescribing and Administration
Can be fitted at any point during the menstrual cycle
- If fitted in the first 5 days is immediately effective
- If fitted at any other time, another form of contraception (e.g. condoms) will need to be used for the first 7 days after implanting
Fitting the implant
- Fitted on the medical aspect of the upper arm
- Goes just under the skin (subcutaneous)
- Local anaesthetic given to numb the area
- Feels similar to an injection
- Area may be sore for 2-3 days after. The implant can be felt under the skin
Removing the implant
- Can be removed at any time, should be removed after 3 years
- Normally done in clinic by a GP
- Local anaesthetic used, a small incision is made, and the implant removed
- In some patients, the implant may be difficult to feel, and these patients will need to be referred to have it removed via guided USS.
- If the patient intends to carry on using implants as contraception, a further implant can be fitted at the same time as the old one is removed.
- After permanent removal – fertility returns quickly. Advise the patient pregnancy can occur before periods have returned to normal.
After pregnancy
- Can be fitted on or before day 21 after to birth to provide immediate protection
- If fitted after 21 days, additional contraception (e.g. condoms) will have to be used for 7 days
After abortion / miscarriage
- Can be fitted immediately for immediate protection
Drug Interactions
Enzyme inducting drugs
- E.g. St John’s Wort
- TB, epilepsy and HIV medications
- If the patient also takes any of these, it is recommended to use additional contraception (e.g. condoms) for the duration of the treatment and for 4 weeks after
Unlike some other forms of contraception, the implant is not affected by diarrhoea, vomiting or antibiotics.