Localization and Referral of Deep Contraceptive Implants

A deep implant is a rod that lies deeper than the subdermal plane, in or beneath the fascia or muscle, and cannot be palpated or removed through a simple incision. It is uncommon but important because deep rods lie close to the median, ulnar and medial antebrachial cutaneous nerves and to the brachial vessels. Blind exploration risks nerve and vessel injury.

Indications for localisation.

• A rod that cannot be felt after insertion or at a later visit.

• A rod that is felt but cannot be removed at routine removal.

• Suspected migration of a rod.

• Pain, numbness, tingling or weakness in the arm after insertion.

• Pregnancy in a patient whose implant cannot be palpated.

Risk factors. Deep placement during insertion, inexperienced provider, inserting at the wrong site, a thin arm, and a rod pushed in instead of released.

Initial steps.

• Confirm the type of implant, the arm and the date of insertion from the card or records.

• Examine the arm for scars and palpate the whole inner arm and axilla.

• Test sensation and strength in the median, ulnar and radial distributions and check the radial pulse and capillary refill.

• Do a pregnancy test.

• Tell the patient honestly what has happened and what will be done.

• Give condoms or another method until the rod is located, because a non-palpable implant may not be giving protection.

Imaging.

• First line: high-frequency linear ultrasound (10 MHz or more, ideally 13 to 18 MHz) of both arms. The rod appears as a bright line with a shadow behind it. Record the depth from the skin, the relation to fascia and muscle, and the distance from vessels and nerves. Mark the skin over the rod.

• If ultrasound does not find the rod: plain X-ray or CT of the arm, because the etonogestrel rod contains a radio-opaque material; levonorgestrel rods may not be visible on plain X-ray. Use MRI as an alternative.

• If the arm is negative: image the chest, because rare migration of an etonogestrel rod to the pulmonary vessels has been reported.

• Serum etonogestrel assay can confirm that an implant is present when imaging is negative, but it is available only at specialist laboratories.

Referral.

• Refer to a surgeon, gynaecologist or other specialist experienced in deep implant removal, with the imaging results, the implant type and date and a note of the examination findings.

• Refer urgently, within days, for neurological deficit, severe pain, signs of vascular injury or suspected infection; otherwise refer promptly, because fibrosis makes later removal harder.

Removal by the specialist.

• Remove under local or regional anaesthesia in a procedure room or theatre with ultrasound or fluoroscopy.

• Make an incision close to the rod, dissect carefully away from nerves and vessels and take the whole rod.

• Do not use blind probing or traction.

• For rods lying next to vessels or nerves, involve a vascular or plastic surgeon.

Complications of deep implants and their removal.

• Nerve injury: numbness, tingling, weakness or pain; urgent neurological assessment and referral.

• Vascular injury or haematoma: pressure, urgent surgical review.

• Infection: flucloxacillin 500 mg orally four times daily for 5 to 7 days.

• Incomplete removal or rod fragments: image again and refer.

• Pregnancy with a non-palpable implant: exclude ectopic pregnancy by ultrasound and manage accordingly.

• Persistent scar or chronic pain: refer for specialist review.

If the rod cannot be found. Give a reliable alternative method and a letter that states the implant type and date, the imaging done and the plan, because the implant may remain in place with uncertain function.

Contraception. Provide backup contraception, or switch to another method, until the rod is located and removed or its presence is confirmed by assay. Do not rely on a non-palpable implant for protection.

Follow up. Review the arm and neurological function 1 to 2 weeks after removal and again at 3 months if symptoms persist.

Documentation. Record the insertion details, imaging results, referral and outcome. Record the event as an adverse event with the product name and batch number and report it through the pharmacovigilance system.

Special groups. Patients who report pain or numbness after insertion need prompt examination, not reassurance alone. Breastfeeding and thin patients have a higher risk of deep placement.

Referral and escalation. Refer every patient with a non-palpable or deep implant, unexplained neurological symptoms or suspected migration, and every patient who became pregnant with a non-palpable implant.