Experiences of localization and removal of non-palpable subdermal contraceptive implants with ultrasound

Objective The aim of this study was to present experiences in localization and removal of non-palpable subdermal contraceptive implants with ultrasonography. Methods Medical records from January 1, 2016, to April 30, 2018, were retrospectively reviewed for 21 patients who were referred to a single institution and had an impalpable implant despite following the removal instruction. In all the cases, more than one attempt was made to remove the implant before referral. The rod was detected using radiography and ultrasonography. In all the cases, localization of the single implant was achieved with ultrasonography. The distal depth of the rod was measured, and skin marking was made following the echogenicity. The implants were subsequently removed under anesthesia. Results In 18 cases, the rods were localized using ultrasonography and successfully removed under local anesthesia. In the other three cases, removal with local anesthesia failed. Although the rod was detected successful with ultrasonography, the implants were removed under general anesthesia in the operating room. The depth from skin to rod, measured with ultrasonography, was >12.0 mm in all the cases and located deep in the muscular layer in the failure cases. The depth of the implants positively correlated with the time spent for removal (r=0.525; P=0.015). Conclusion High frequency ultrasonography is a highly accurate tool for localization and measurement of the skin-to-rod depth. It is also useful for removing non-palpable implants. If the depth of the implant is >12.0 mm, removal of the implant in the operating room under general anesthesia is recommended.