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

Disadvantages

Contraindications WHO 4

Caution

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