This study will be the first to establish pharmacokinetic curves for the etonogestrel contraceptive implant with scapular subdermal insertion. By obtaining this pharmacokinetic data, the investigators can compare this data to already published pharmacokinetic data with conventional implant insertion. This comparison can provide some reassurance that the absorption and distribution of etonogestrel from the contraceptive implant with scapular insertion is similar to that found with conventional insertion. With similar pharmacokinetic properties, the investigators would expect scapular insertion of the implant to maintain similar contraceptive efficacy for the populations of women that may benefit from this alternative insertion site. Preliminary safety data will also enrich the understanding of any potential insertion site side effects with subdermal scapular implant insertion, as the investigators currently only have a single case report with side effect outcomes. The investigators can then use this pilot data to support future larger investigations on subdermal scapular implant insertion given its complete avoidance of the neurovascular complications associated with arm insertion.

The etonogestrel contraceptive implant (Nexplanon®) remains the most effective hormonal contraceptive method available in the U.S. The contraceptive implant is routinely inserted just beneath the skin on the inner-side of the non-dominant arm, but insertion at this site has resulted in rare, yet potentially morbid complications. These complications are due to the close proximity of major neurovascular structures (e.g. basilic vein, ulnar nerve) in the sulcus between the biceps and triceps muscles. Insertion of the implant deep in the arm has resulted in severe complications including migration of the implant into the pulmonary vasculature and neurological injury at the time of implant removal. Though these complications are rare, their report directly led to changes in the manufacturer's mandatory insertion training to move the implant insertion site inferiorly, though it is unlikely that this change will completely remove the risk of these rare insertion complications.

In addition to the rare complications of deep implant insertion in the arm, patients with specific medical conditions are also not ideal candidates for this standard insertion site. Patients with psychotic illnesses or development delays often require reliable contraception, but the arm insertion site for the implant is easily accessible and injuries can result from self-removal attempts among these patients. Furthermore, patients with muscular dystrophy disorders may not have adequate tissue in this region of the arm to buffer the implant from the underlying neurovascular structures. In order to address the needs of these patient populations, insertion of the contraceptive implant at an alternative subdermal scapular site has been reported in the literature. This insertion just beneath the skin overlying the inferior edge of the scapula represents an ideal alternative location for the contraceptive implant due to its location far from danger zones of neurovascular structures, inaccessibility to patients with mental illnesses, and underlying bony structure preventing unintentional deep insertion. However, more data are needed regarding the rate of drug absorption and overall safety with etonogestrel implant insertion at this alternative site.

The study will address this knowledge gap by piloting contraceptive implant insertion at this alternative scapular site among five healthy, reproductive aged women. The investigators will insert contraceptive implants at this alternative scapular site and conduct serial measurements of the amount of drug (etonogestrel) circulating in each participant's system over the course of one year. These measurements will allow us to compare the amount of circulating drug from the contraceptive implant between this alternative insertion site and the already published amounts found with standard insertion in the arm. The investigators will also ask participants about any insertion site related side effects and also general implant-related side effects (e.g. abnormal bleeding, headaches, weight gain) during the course of the study. This will provide preliminary side effect data to help us better understand patient experience with this alternative insertion site. Ultimately, the investigators hypothesize that this study will provide reassuring data that can support future larger investigations on this alternative scapular insertion site for the implant. This alternative insertion site may allow patients who otherwise are not currently candidates for the most effective hormonal contraceptive method to uptake contraceptive implants in a safe manner. This research will also allow healthcare providers to discuss an alternative site for the contraceptive implant for those patients concerned about the potential risks of deep arm insertion, thus improving patient-centered options for contraceptive implant provision.

Inclusion Criteria:

• Healthy women

Exclusion Criteria:

• Any contraindications to etonogestrel implant use based on the US Medical Eligibility Criteria for Contraceptive use (defined as class 3 or 4 recommendation)18
• Any known liver conditions that could affect drug metabolism (e.g. cirrhosis, hepatitis)
• Currently taking any medications or supplements known to be CYP3A4 inducers/inhibitors19
• Body-mass index less than 18.5kg/m2 or greater than 30kg/m2
• Currently pregnant or planning to become pregnant in the next 12 months

12 months