This article reviews the advantages and disadvantages of
progestogen-only
contraceptive implants in light of the development of
Implanon, a new, single-rod,
etonogestrel-releasing system. Implants rapidly produce serum
progestogen levels sufficient to ensure
contraception for 1-5 years. The steady release ofprogestogen avoids the peaks and troughs associated with
oral contraceptives, the profound ovarian suppression observed with depot
injections and the need for user compliance. Implants have few serious complications.
Ectopic pregnancy rates are low, and follicular
hypertrophy is generally self-limiting. The principal acceptability limitation to both users and providers of
Norplant is insertion and removal.
Implanon is easy to insert and remove with minimal complications and
pain. The main adverse event causing discontinuation of implants is a change in
bleeding pattern. However, with good counselling, this is well tolerated by most women. Implants thus provide an effective, safe, economical and convenient alternative to oral,
injectable or intrauterine
contraceptives.
Implanon is an extremely effective single-rod implant with a Pearl index of 0. It employs a new
polymer and a less androgenic
progestogen. These features provide easier insertion and removal for both users and clinicians, a more stable release rate and potentially fewer adverse androgenic effects compared with existing formulations.