Nonpalpable ultrasonographically not detectable Implanon rods can be localized by magnetic resonance imaging

Recently, the contraceptive implant Implanon has been introduced in several European countries. In comparison to the six-capsule preparation Norplant, the removal of this single-rod system should be associated with less complications. However, the removal of nonpalpable Implanon rods can be difficult because the implant is not always visible with ultrasound. The aim of this study was to find a radiologic method for the localization of Implanon implants that are nonpalpable and can not be detected by ultrasound. X-ray, ultrasound, computed tomography, and magnetic resonance imaging (MRI) were investigated as methods to localize Implanon in a pig chest preparation and in a woman with a nonpalpable implant. The implant in the woman could be localized unequivocally only by MRI. We conclude that MRI is the best method for the unequivocal localization of nonpalpable, ultrasonographically not detectable Implanon rods. To avoid unnecessary scar tissue formation, it may be appropriate to defer surgery for the removal until definitive localization.