Pilot study of a novel, alternative subdermal scapular insertion site for the etonogestrel contraceptive implant

To assess the pharmacokinetics and pharmacodynamics of the etonogestrel (ENG) contraceptive implant when inserted at an alternative scapular site.

We conducted a pilot study of healthy, reproductive-age females who underwent subdermal insertion of an ENG implant over the inferior edge of the nondominant scapula (scapular insertion). We measured serum ENG levels over 1 year at nine time points. Participants completed questionnaires on insertion site and bleeding side effects. We collected photographs and video recordings of insertion and removal techniques.

We enrolled five participants (as prespecified), their median age was 26.0 years (range: 19.6-30.3), and median body mass index was 25.0 kg/m² (range: 22.0-28.0). All serum ENG concentrations remained >90 pg/mL and were within the range of published data for arm insertion of ENG implant at all time points. The mean serum ENG level was 511.7 pg/mL (±168.2) at 1 week and 136.6 pg/mL (±21.8) at 12 months. During the first week after insertion, four of five participants noted insertion site pain with a median pain score of 2 (range 1-3), but all noted resolution by week two. Participants reported variable bleeding patterns consistent with standard ENG implant placement. At the end of the study, all participants reported satisfaction with the implant and would recommend scapular insertion to a friend.

Scapular insertion of the ENG contraceptive implant has similar pharmacokinetics to arm insertion over 1 year of use. This novel, alternative site was well tolerated and demonstrated similar bleeding side effects to standard arm insertion.

Subdermal scapular insertion of the etonogestrel contraceptive implant demonstrated similar pharmacokinetics to arm insertion over 1 year of use. Our pilot data support scapular insertion as an alternative site for ENG contraceptive implants, which could be beneficial for certain patient populations.