Use of the Etonogestrel-Releasing Contraceptive Implant

Jaclyn Grentzer; Colleen McNicholas; Jeffrey F Peipert


Expert Rev of Obstet Gynecol. 2013;8(4):337-344. 

In This Article

Advantages & Disadvantages

The ENG implant is a very safe method of contraception. The rates of anemia, hypertension, gallbladder disease, diabetes, pelvic inflammatory disease, thromboembolic events, cardiovascular events and neoplastic diseases are similar to women not using implants.[20]

There are numerous advantages and health benefits of the ENG implant. Advantages include an extremely low failure rate, ease of use, discreetness and safety when implanted both immediately postpartum and postabortion. The method is easy to use with rapid insertion and removal times. The average length of time for insertion of the implant is less than 1 min and for removal is less than 4 min.[21] Furthermore, after insertion, no additional attention is required by either the user or the provider until time of removal. This makes the implant an excellent contraceptive option for women who have trouble with user-dependent methods that require monthly, weekly, daily or coital attention. The ENG implant is also discreet. While palpable under the skin, the implant is not visible, with the exception of the possibility of a small scar at the insertion site.

Use of the ENG implant has also been shown to have benefits beyond pregnancy prevention. In a study of 330 subjects using the ENG implant for a total of 474 woman-years, acne improved in 61% of women. This same study also demonstrated that 81% of women with dysmenorrhea at baseline reported decreased symptoms at the end of the study period.[22] Similarly, implant users reporting a history of endometriosis prior to method initiation reported markedly improved dysmenorrhea scores at 12 weeks post-insertion.[23]

Like other forms of contraception, the ENG implant reduces the risk of ectopic pregnancy simply by effectively preventing all pregnancies. If a pregnancy does occur, ectopic pregnancy must be ruled out as progesterone can impact cilia in the fallopian tube and increase the likelihood of tubal implantation.[24]

Finally, the ENG implant is associated with a rapid return to fertility. Eighty eight percent of women return to their normal menstrual cycle following removal of the ENG implant,[22] and ovulation resumes within 3 weeks of removal in more than 90% of users.[17,25] This is in contrast to a 6- to 18- month delay for depo medroxyprogesterone acetate (DMPA). Return to fertility in the 12 months after removal are comparable with the general population of women who are attempting conception.[26–28] A study evaluating 200 implant users found that 95.8% (n = 24) of women using no family planning methods following removal of their implant conceived within 12 months.[29]

The primary disadvantage reported by users of the ENG implant is irregular and unpredictable bleeding. Bleeding patterns can range from amenorrhea to frequent and prolonged bleeding (Table 1).[30,31] There is no way to predict the bleeding pattern that an individual ENG implant user will experience. A meta-analysis evaluated bleeding patterns over 2 years in 780 women. More than 3000 90-day reference periods were assessed. Of the women evaluated, 22% had amenorrhea, 34% infrequent bleeding (<three episodes of bleeding or spotting), 7% frequent bleeding (>five episodes of bleeding) and 18% prolonged bleeding (≥one bleeding episode lasting >14 consecutive days).[31] Discontinuation rates secondary to irregular and unpredictable bleeding can be variable. An integrated analysis of 11 clinical trials reported a rate of 11.3% (105 out of 942), but others have suggested higher rates.[10] This variation implies how essential it is to discuss bleeding changes with potential users prior to insertion.

Weight gain is a common reason cited for discontinuation across most methods of contraception. Early studies of ENG implant users showed a mean weight gain of 0.82, 1.15 and 2.50 kg, after 1, 2 and 3 years of use, respectively.[32,33] An integrated analysis of 11 international trials found that 69% of women reported weight gain with ENG implant use; however, only 13.4% of women reported this as an adverse event. Of that 69%, 25% reported a weight gain of 0.1–2.5 kg, 24% gained 2.6–5 kg, 9% gained 5.1–7.5 kg and 11% gained more than 7.5 kg.[34] A recent study of 4133 contracepting women confirmed that perceived weight gain for most women represents true weight gain with a sensitivity and specificity of 74.6 and 84.4%, respectively. Using perceived weight gain as a surrogate marker of objective weight gain, this same study found that ENG implant users were more likely (relative risk: 1.29; 95% CI: 1.1–1.51) to perceive a weight gain when compared with copper IUD users.[35] Whether implant users gain significantly more weight than other contraceptive method users or women using no contraception remain to be determined.

Other less commonly reported reasons for discontinuation include emotional lability/mood changes, headache, breast discomfort and acne.[10,34] Emotional lability and mood changes are impossible to predict. Very often, these changes are due to stresses and other factors in a woman's life rather than the method of contraception. A careful and detailed history can assist in differentiating life changes versus mood changes due to hormonal effect. Headaches are reported by up to 25% of women and are the most common non-menstrual side effect noted by users. This side effect is similar in frequency to complaints of headache reported by oral contraceptive users. Breast discomfort may be reported by 10–15% of implant users, but this typically decreases with increased duration of use. Acne is the most common skin complaint, and also may be reported in 10–20% of implant users. It is interesting that more women reported improvement in acne than worsening. As stated earlier, a study of women using the ENG implant for 2 years noted that more than 60% of women with acne at baseline reported decreased acne. Approximately 16% of users with no acne at baseline developed new acne.[22] For women reporting increased acne, good skin hygiene and common acne therapies are often helpful. Other adverse reactions causing discontinuation in clinical trials included vaginitis, abdominal pain and pharyngitis.[10,34]

There is conflicting evidence regarding bone mineral density (BMD) changes in ENG implant users. In a 2-year study of 44 women using the ENG implant, there was no difference in BMD change when compared with nonhormonal IUD users.[36] However, another study of 50 women who had been using the ENG implant for at least 2 years were found to have a significantly lower BMD at the distal radius and ulna than women using nonhormonal contraceptives. However, this study also reported no difference in BMD in the lumbar spine or femur, the two sites most frequently implicated in osteoporotic fractures aside from the wrist.[37] While the data are conflicting, no studies have demonstrated an increased risk in pathologic fracture in women using the ENG implant. Overall, experts believe that ENG implant does not significantly affect bone health.

Insertion and removal complications constitute another area of possible disadvantage to ENG implant use; however, these complications are rare. In a study of 941 ENG implant users, 1% experienced complications at implant insertion including: implant retained in the needle of the applicator, bleeding, hematoma formation and difficult insertion. Of the 900 ENG implant users who underwent implant removal, 1.7% experienced complications: breaking of the implant, difficulty locating the implant, difficult removal due to deep insertion and fixation of implant to adjacent tissue.[10,34]

Finally, as with all nonbarrier methods of contraception, the ENG implant does not protect against sexually transmitted infections (STIs). All sexually active women, especially young women and women at high risk for STIs, should be counseled on prevention of STIs using barrier methods, such as condoms.