Only one progestin implant is available in the US. It is a 4-cm, match-sized single-rod implant that can be inserted through a trocar subdermally; the insertion site is over the triceps—about 8 to 10 cm from the medial epicondyle of the humerus and 3 to 5 cm posterior to (below) the sulcus (groove) between the biceps and triceps muscles. The groove between the bicep and tricep should be avoided. No skin incision is required. The implant releases etonogestrel (a progestin) at an average rate of 50 mcg/day at 12 month. The implant provides effective contraception for up to 3 years (although in some studies, efficacy persisted up to 5 years). Before inserting or removing this implant, health care practitioners must complete 3 hours of manufacturer-sponsored training.
The implant currently available is bioequivalent to the previously used implant but is designed to be radiopaque to make it easier to locate at the time of removal. Also, the insertion applicator is easier to use, so that the implant is less likely to be inserted too deeply.
A subdermal implant may be inserted at any time during the menstrual cycle. However, if unprotected intercourse has occurred within the past month, another contraceptive method should be used concurrently until pregnancy can be reliably excluded by a negative pregnancy test or by the subsequent occurrence of menses. If the implant is inserted during the first 5 days of menstrual cycle, no backup contraceptive method is needed. If it is not inserted during this time frame, a backup contraceptive method should be used concurrently for at least 7 days. The implant may be inserted immediately after spontaneous or induced abortion or immediately postpartum regardless of breastfeeding status.
The most common adverse effects are similar to those of other progestins (irregular vaginal bleeding, amenorrhea, headache).
Removing the implant, which is usually done when the implant is no longer effective, requires a skin incision. After implant removal, ovarian activity normalizes immediately.
Other contraceptive implants are available elsewhere in the world.
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