Subdermal Contraceptive Implants

Progestin implant contraceptives are devices that are placed subdermally and provide contraception for several years. One implant is available in the United States and releases etonogestrel (a Progestin implant contraceptives are devices that are placed subdermally and provide contraception for several years. One implant is available in the United States and releases etonogestrel (aprogestin) at an average rate of 50 mcg a day at 12 month. The implant provides effective contraception for up to 3 years (although in some studies, efficacy persisted up to 5 years).

Pregnancy rates in the first year are 0.05% with perfect use; rates with typical use are the same (1).

The implant 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. Before inserting or removing this implant, health care professionals must complete 3 hours of manufacturer-sponsored training.

The implant currently available in the United States 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. Other contraceptive implants are available elsewhere in the world.

If the implant is inserted during the first 5 days of the menstrual cycle, no backup contraceptive method is needed. If it is inserted at other times of the menstrual cycle, the patient should be assessed for pregnancy risk factors to determine whether pregnancy testing is needed, and a backup contraceptive method should be used concurrently for at least 7 days. 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.

The implant may be inserted immediately after or within 7 days of spontaneous or induced abortion or immediately postpartum or within 4 weeks regardless of breastfeeding status.

There are few contraindications for the progestin implant, and these are similar to progestin-only oral contraceptives.

The most common adverse effects are similar to those of other progestins (irregular vaginal bleeding, amenorrhea, headache).

Drug interactions with hormonal contraceptives can decrease contraceptive efficacy or alter the therapeutic efficacy of concurrent medications.

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.