Ultrasound localisation and removal of non-palpable Implanon implants

Implanon is the trade name for a contraceptive implant that releases etonogestrel over a 3-year period. The rod is inserted into the subdermis of the upper arm. The implant should be palpable and easily removed through a small incision.

To determine whether ultrasound is an accurate means of localising and guiding removal of non-palpable Implanon implants.

All patients referred to The Northern Hospital, between March 2002 and October 2005, for localisation and/or removal of their non-palpable Implanon implants were included in this study. Ultrasound was used to locate the implants, the implant was considered localised when a linear echogenic rod with posterior acoustic shadowing was identified. When removal of the implant was requested and the implant was clear of neurovascular structures, blunt dissection was performed under ultrasound control and the implant was extracted. If the implant was considered too close to major neurovascular structures, the position of the implant was marked and the patient was referred for surgical removal.

Thirty-four women were included in the study. In 33 patients the implant was identified. In one patient no implant was found and its absence was confirmed by serum assay. Twenty-four patients were referred for implant removal. In 20 patients the implant was successfully removed under ultrasound guidance. In the other four patients the implant was close to neurovascular structures. The position of the implants was marked and surgical removal was successfully performed.

Ultrasound is highly accurate at localising and guiding removal of non-palpable Implanon implants.