Sub-dermal implants

Sub-Dermal Implants (eg Implanon)

Implanon is a progesterone-releasing rod that is inserted under the skin on the inside of the upper arm, just above the elbow. It is a very effective long-acting reversible method of contraception (LARC). It remains active for 3 years and with a very low failure rate and low cost, it is becoming a more popular method of contraception. However it needs a specially trained practitioner to insert the device and it offers no protection against STIs.

Advantages

Reliable and reversible with only a 0.1% failure rate.
Prolonged action
No pills to remember to take
Relatively easy to insert under local by trained practitioner (Nurse or Doctor)
Safe for breast-feeding mums – insert 6 weeks post-partum.
Cost effective method.
No teratogenic effect – though would need to be removed if pregnancy occurred

Disadvantages

Some discomfort on insertion, local swelling and bruising with risk of infection.
Some discomfort on removal, but single rod easier to remove than discontinued versions.
Menstrual disturbance – irregular bleeding, amenorrhoea – give 6 months to settle in.
Progesterone side effects – weight gain, mood changes, acne, and loss of libido.
No protection against STIs
If on enzyme accelerators, may require 2 rods inserted.

Contraindications WHO 4

Allergy to progesterone or liver adenoma
Recent breast cancer, not in remission
Acute porphyria
Recent trophoblastic disease.
Pregnancy
Undiagnosed genital tract bleeding

Caution

Enzyme inducers (? 2 implanon rods or choose alternative method)
Past history of symptomatic ovarian cysts

The commonest reason for discontinuation with this method is the irregular bleeding therefore, patients should be carefully counseled about this, prior to insertion. They need to be advised that implanon needs a 6 month settling in period and by this time the first surge of hormone release should have settled down along with some of the menstrual problems. Failing this and if no contraindications, then mefanamic acid or the addition of premarin or a COC, can be tried. The woman should also be advised about sexual health and the use of condoms for safer sex. If she has any concerns, offer STI screening.

Method of Action

Implanon is a single 40mm rod, just 2mm in diameter and is inserted sub-dermally using a pre-loaded applicator, under local anaesthetic. It is placed just above the sub-cubital fossa on the upper arm. It releases the hormone etonogestrel which inhibits ovulation and acts on cervical mucous and endometrium. Directly after insertion there tends to surge of higher level of hormone released, which tends to settle down after a few weeks.

Insertion

Should be inserted day 1 – 5 of normal menstrual cycle. Or, any time in the cycle if no chance of pregnancy, with additional contraception for a further 7 days. Post delivery, insert at 21 days but if the woman is breast feeding the insertion should be delayed until breast feeding is established, at around 6 weeks. Following a first trimester abortion, the device can be inserted straight away.

The patient should be counseled, prior to insertion, about the side effects that she might experience and the altered menstrual pattern. Discuss sexual health and check smear status. Although no formal regular check up needs to be arranged she needs to be given written instructions of when the device needs to be changed, with an invitation to return if she has any problems or she wishes it to be removed earlier. A PAL should be given. Implanon does not require annual monitoring of BP.

References

Glasier,A Bebbie,A Family Planning and Reproductive Health Churchill Livingstone
Guillebaud,J Contraception Today. Taylor and Francis
www.ffprhc.org.uk