Although the risk of neurovascular injury and implant migration with Nexplanon has been known since 2016 reports have continued to come in, with 126 cases of implant migration reported to the MHRA up to June 2019. Eighteen of these cases mention migration to the lung.
Worldwide there have been 107 reported cases of implant migration to the pulmonary artery and lung between the product's launch in August 1998 and September 2019. Reports of haematoma and excessive bruising at the insertion site and dyspnoea have also been received.
Potential risk factors
Although no specific risk factors have been identified, potential risk factors include: deep insertion; insertion in an inappropriate site; and insertion in thin arms.
In response to the continued reports MSD, the manufacturer of Nexplanon, further explored the anatomy of the arm to identify a site with the lowest number of vascular/neurological structures. The new insertion site is in an area overlying the triceps muscle, a location generally free of major blood vessels and nerves.
Updated instructions for insertion have been added to the product information for Nexplanon, including an amended diagram showing the new insertion site, the correct position of the arm for insertion and how to view the needle to avoid deep insertion.
Advice for healthcare professionals
Healthcare professionals undertaking subdermal insertion of the implant should ensure that they:
- have received appropriate training and accreditation
- have reviewed the updated guidance on how to correctly insert the implant
- show the woman how to locate the implant and advise her to do this occasionally and to report any concerns promptly
- localise any implant that cannot be palpated (eg, by imaging the arm) and to remove it at the earliest opportunity - chest imaging should be performed if it cannot be located in the arm
The MHRA advice states that implants inserted at the previous site that can be palpated should not pose a risk and need not be moved to the new site. Implants should only be replaced if there are concerns regarding their location or if routine replacement is due.