AKT · Obstetrics & gynaecology/Contraceptionlow yield

Contraceptive implant (Nexplanon)

Etonogestrel subdermal rod — LARC; inhibits ovulation

Overview

A single subdermal progestogen rod lasting 3 years — the MOST EFFECTIVE reversible method (<1% failure, "fit and forget"). Inhibits ovulation. The main drawback is an unpredictable bleeding pattern, the commonest reason for early removal.

Recognise

LARC: 3 years, user-independent → lowest typical-use failure of all methods
Inhibits ovulation
Bleeding pattern unpredictable (amenorrhoea, infrequent, or frequent/prolonged)
Very few contraindications (current breast cancer UKMEC 4)

Red flags

Current breast cancer (UKMEC 4). Enzyme-inducing drugs reduce efficacy (a rare LARC limitation)

Differentials & how to tell them apart

Levonorgestrel IUSintrauterine LARC; tends to lighten/stop periods and treats heavy menstrual bleeding

Depot injectionprogestogen every 13 weeks but BMD loss + delayed fertility return — implant has neither

Progestogen-only pilldaily adherence required — implant removes that risk

Investigations

History/exclude pregnancy; trained fitter for insertion. No BP/oestrogen concerns.

Management

Subdermal implant when the most effective, adherence-free reversible method is wanted

1Offer as first-line LARC (most effective). Insert; counsel that bleeding pattern is unpredictable.Gate: Enzyme-inducing medication (e.g. some antiepileptics, rifampicin) reduces implant efficacy → consider an alternative (e.g. copper IUD/IUS unaffected)
2Troublesome bleeding → investigate/measure, can offer a COCP course or removal.

Etonogestrel rod — subdermal upper arm; effective for 3 years

Key points

Fertility returns rapidly after removal. Unlike the injection, no effect on bone density and no fertility delay.

Monitor & prognosis

Bleeding pattern; removal/replacement at 3 years.

Immediately reversible on removal.

Source: FSRH UKMEC 2016; FSRH implant guidance