The brand name product Implanon is no longer commercially available in the U.S., and has been replaced by Nexplanon.

Nexplanon and Implanon are both long-acting, reversible hormonal contraceptive implants that contain etonogestrel, a hormone that prevents ovulation (the release of an egg from an ovary). Etonogestrel, a progestin hormone, leads to changes in the cervical mucus and uterine lining, making it harder for sperm to reach the uterus and harder for a fertilized egg to attach to the uterus. Etonogestrel is slowly released from a small plastic rod implanted in the skin of your upper arm.

Why is Nexplanon radiopaque? The Nexplanon implant is radiopaque because it contains a small amount of barium sulfate so that the implant can be seen by your doctor with an X-ray or other imaging tool. Being radiopaque is an advantage as physicians can verify presence of the implant after insertion. The rod can remain in place and provide continuous contraception for up to 3 years.