Etonogestrel Implant Duration and Placement
The etonogestrel subdermal implant (Nexplanon) is inserted under the skin of the inner upper arm and remains effective for up to 5 years, after which it must be removed and can be immediately replaced if continued contraception is desired. 1
Duration of Contraceptive Effect
The FDA-approved duration for the etonogestrel implant has been extended to 5 years 1. This represents an update from the previous 3-year approval, based on robust evidence demonstrating continued efficacy:
- Years 1-3: Established efficacy with pregnancy rates <1 per 100 woman-years 2, 3
- Years 4-5: Research demonstrates zero pregnancies during extended use, with calculated failure rates of 0 per 100 woman-years (95% CI: 0-1.48 at 4 years; 0-2.65 at 5 years) 4
- Additional prospective data confirms no pregnancies occurred during years 4-5 of use 5
The implant must be removed by the end of the fifth year 1. Serum etonogestrel levels remain above the ovulation threshold (90 pg/mL) throughout the 5-year period, even in women across all BMI categories 5.
Location and Placement
The implant is inserted subdermally (just under the skin, not deep) at a specific anatomical location 1:
- Site: Inner side of the non-dominant upper arm
- Position: Overlying the triceps muscle, approximately 8-10 cm (3-4 inches) from the medial epicondyle of the humerus
- Depth: 3-5 cm (1.25-2 inches) posterior to the sulcus (groove) between biceps and triceps muscles
This precise location avoids large blood vessels and nerves. Deep insertion is a critical error that can make the implant non-palpable and extremely difficult or impossible to remove 1.
Replacement Frequency
- Single insertion lasts up to 5 years 1
- Removal required by end of year 5 1
- Immediate replacement possible at time of removal if continued contraception desired 1
- Rapid return to fertility occurs after removal 6
Important Clinical Considerations
Backup contraception timing varies by insertion timing 2:
- If inserted within first 5 days of menstrual bleeding: No backup needed
- If inserted ≥6 days after bleeding started: Use barrier method for 7 days
- Postpartum (breastfeeding): Insert after 4 weeks postpartum; use barrier method for 7 days 1
- Postpartum (not breastfeeding): Insert 21-28 days postpartum 1
The implant contains 68 mg etonogestrel plus 15 mg barium sulfate (for radiographic visibility) 1. It should always be palpable after proper insertion—if non-palpable, imaging is required to locate it 1.
Common pitfall: The most frequent reason for discontinuation is unpredictable bleeding patterns, not contraceptive failure 3. Counseling patients about expected bleeding changes improves continuation rates.