Acute Ulnar Neuropathy After Uncomplicated Contraceptive Implant Insertion: A Case Report

To avoid the nerves and blood vessels of the upper extremity, the subdermal contraceptive implant Nexplanon (N.V. Organon, Oss, The Netherlands) is inserted into the subdermis at a location 8-10 cm proximal to the medial epicondyle of the humerus and 3-5 cm posterior to the groove between the biceps and triceps muscles. Ulnar nerve injury is a known but extremely rare complication associated with implant insertion. Risk factors for ulnar nerve insult include inadvertent deep insertion, device migration, and an underweight patient. This is a case report of an obese 40-year-old female who presented four days after uncomplicated contraceptive implant insertion with symptoms consistent with an acute ulnar neuropathy, despite the implant being located in the proper superficial location. Symptoms resolved soon after implant removal. This unique presentation may be explained by the aberrant anatomy of the ulnar nerve. It is important for clinicians to be able to recognize and treat this rare complication of contraceptive implant insertion, even in a patient who possesses no risk factors for ulnar nerve injury.