Timing of insertion and removal
The timing of insertion of Implanon is based on the patient’s menstrual cycle and current contraceptive method:
- For a woman who is not using a hormonal contraceptive, insertion should take place during the first 5 days of menses.
- For a woman who is actively using a cyclic hormonal contraceptive, the device should be inserted during the hormone-free interval.
- For a woman on a continuous hormonal contraceptive, Implanon can be inserted at any time.
- After pregnancy, the device can be inserted 3 or 4 weeks after delivery.
The Implanon rod can be removed at any time. It must be removed after 3 years of use.
The Implanon rod was originally studied in women who weighed no more than 130% of their ideal body weight. The effectiveness of Implanon in obese women has not been thoroughly assessed in a large population study.
Side effects: Principally, bleeding
Implanon is not associated with loss of bone mineral density (BMD). In one study that compared the BMD of Implanon users with that of IUD users, no decrease was noted in the BMD of either group over a 2-year period.7 Preservation of BMD may be due, in part, to the observation that women who use Implanon appear to have a greater circulating estradiol concentration than women using depot medroxyprogesterone acetate.8
Frequent or unpredictable bleeding (or both) is the major side effect of Implanon. In one study of 324 women who used Implanon, continuation rates were 75%, 59%, and 47% at 1 year, 2 years, and 2 years-9 months, respectively. Of women who discontinued Implanon, 91% did so because of frequent or unpredictable bleeding or both.9 In another study, the continuation rate was 66% at 1 year.10
Women using Implanon who have higher circulating estradiol levels and ovarian follicle activity may be at greater risk of abnormal patterns of bleeding.11 In a preliminary report, women with prolonged bleeding in association with Implanon were randomized to various treatment regimens, among which were doxycycline, 100 mg twice daily for 5 days, or placebo. Doxycycline treatment significantly reduced prolonged bleeding compared with placebo (4.8 days [95% confidence interval (CI), 3.9 to 5.8 days] versus 7.5 days [95% CI, 6.1 to 9.1 days], respectively).12 Women using progestin contraceptives who have abnormal uterine bleeding have elevated levels of endometrial enzymes, such as matrix metalloproteinases and neutrophil elastase, that prevent epithelial tissue repair. Doxycycline may inhibit these enzyme systems and enhance repair of endometrial epithelial tissue. Whether doxycycline will become a widely used treatment for prolonged bleeding associated with Implanon remains to be determined in additional clinical trials.
The bonus of being out of sight, out of mind
Long-term reversible contraceptives allow the patient to “insert it and forget it.” This feature significantly increases the contraceptive efficacy of the method and, theoretically, offers an opportunity to reduce the epidemic of unintended pregnancy in the United States.