Abstract and Introduction
The single-rod, etonogestrel-releasing, subdermal implant (ENG implant) is the most effective, long-acting reversible method of contraception available. The failure rate of the ENG implant is 0.05%, which makes it more effective than female sterilization. It is discreet, easy to insert and remove, has no effect on future fertility and is associated with a number of noncontraceptive health benefits. The ENG implant is safe and effective when used in the postpartum and postabortion setting, and in women who have contraindications to estrogen. The most common reason cited for discontinuation is irregular and unpredictable bleeding. However, structured, preinsertion counseling can increase continuation and user satisfaction.
In the USA, each year there are approximately 3 million unintended pregnancies, with nearly half of those unintended pregnancies resulting from contraceptive failure. Long-acting reversible contraceptives (LARCs), including intrauterine devices (IUDs) and subdermal implants, have failure rates of <1%, similar to that of sterilization. The high efficacy of LARC methods is, in part, attributable to the fact they are 'forgettable', and require no effort from the user after insertion. Often, failure rates are reported in two ways: typical-use failure and perfect-use failure. Typical-use failure rates account for inconsistent and incorrect use of a method, and as a result, these rates are lower than reported for perfect use failure rates. This discrepancy between typical and perfect use is best illustrated with user-dependent methods such as oral contraceptive pills. Perfect use is defined as 100% correct and compliant use of a method. Perfect-use failure rate for oral contraceptive pills is <1%. However, typical-use failure rate for the pill is 2–8% per year (9–10% over 3 years). For LARC methods, typical- and perfect-use failure rates are essentially equal. A recent study by Winner et al. found that women using short-term reversible contraception (oral contraceptive pills, transdermal patch or vaginal ring) had a risk of contraceptive failure that was 20-times higher than a similar population of women using LARC. In addition to superior effectiveness, LARC methods have also been shown to have the highest rates of satisfaction and continuation at 12 months. These findings suggest that LARC methods should be offered as first-line contraception to all women who desire pregnancy prevention.
The first contraceptive subdermal implant was developed 45 years ago at Population Council laboratories in New York (USA) and initially marketed and registered for use as Norplant, a six-capsule levonorgestrel (LNG)-releasing system effective for 5 years. Norplant was US FDA approved in 1990, and by 1994, approximately 500,000 American women were using the LNG implant system. By 1996, 70 class action lawsuits and more than 50,000 women had filed claims against Wyeth, its subsidiaries or clinicians who prescribed Norplant. Wyeth never lost a Norplant lawsuit, even in cases that came before a jury. In 1999, after winning three jury verdicts and the dismissal of 14,000 claims, Wyeth provided cash settlements to over 30,000 women who stated that they had not been appropriately counseled about potential side effects of Norplant (e.g., irregular menstrual bleeding, headaches, nausea and depression). Wyeth did not admit to any wrongdoing and claimed that these women experienced the common side effects listed in the Norplant product insert. In 2002, Wyeth won partial summary judgments and dismissal of the claims of the remaining plaintiffs who had not accepted Wyeth's settlement offer. Over time, the LNG implant lost popularity after difficulties in removal began to be reported in the mainstream media. In 2002, Wyeth announced that they did not plan to resume marketing the six-capsule levonorgestrel implant system in the USA.
In 2006, the FDA approved a single-rod, etonogestrel-releasing subdermal implant (ENG implant) or Implanon®. In November 2011, Nexplanon® was released. Nexplanon has a redesigned inserter intended to minimize deep insertions. The active ingredients in the new device are unchanged; however, Nexplanon contains barium that allows for easier radiographic localization.
The ENG implant is the most effective contraceptive method currently available with a 0.05% yearly failure rate.[7,8] In addition, it is easy to insert and remove, requires no post-insertion follow-up, is discreet, has been shown to have additional noncontraceptive benefits, and can be used in women who are not candidates for estrogen-containing methods. Despite these documented benefits, relatively few women in the USA utilize this method.
Expert Rev of Obstet Gynecol. 2013;8(4):337-344. © 2013 Expert Reviews Ltd.