Unintended Pregnancy with Implantable Subdermal Contraceptive Device (Nexplanon): A Case Report

Implanon, an Etonogestrel capsule, containing 68 mg of the synthetic progestin etonogestrel implant, was first introduced in Indonesia in 1998 and approved for use in the U.S. in 2006, as a subcutaneous hormone eluting capsule providing longacting reversible contraception (LARC) [1-4]. Prior to the use of Implanon, short-acting reversible contraceptives (SARC) such as oral contraceptive pills (OCPs), birth control vaginal rings (example Nuvaring), transdermal contraceptive patches, depot medroxyprogesterone acetate (DMPA) injections (DepoProvera) were prescribed [5]. A recent study performed in 2016 compared SARC and LARC, affirming that LARC use provides superior contraception compared to SARC [6,7]. The LARC capsule is inserted by a nurse or physician, with an applicator, into the patient’s nondominant upper arm [8]. The implant manufacturer, Merck Sharp & Dohme (MSD) stated that Implanon had shown to be more than 99% effective in clinical trials, and asserted that there is no contraceptive that is 100% effective [9]. The mechanism of action of Implanon relies on the suppression of ovulation through hypothalamic pituitary ovarian (HPO) axis dysregulation and promotes thickening of the cervical mucus preventing fertilization [10]. Between 1999 and 2011, over 1.4 million women used Implanon [1,2]. An Australian study, published in 2005, found the Implanon failure rate to be 1 in 1000 [11]. This is the only comprehensive study of Implanon failure published [11].