The etonogestrel subdermal arm implant is a popular contraceptive option because it can be easily inserted in the office and provides highly effective long-term results with minimal patient effort.
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One rare complication that providers need to be aware of, however, is implant migration, which can occur over time, reports Pelin Batur, MD, of Cleveland Clinic’s Ob/Gyn & Women’s Health Institute. She was one of the coauthors of a 2018 paper on this topic in Seminars in Radiology.
Implant migration is defined as movement of the 4 cm long device at least 2 cm beyond the site of insertion. The device most frequently only moves a short distance, but if it moves toward the hand, it could potentially cause carpal tunnel symptoms. If it travels upward, it can cause pain in the axillary area and numbness throughout the arm. Most seriously, if it enters the blood stream, it can travel to the lungs, Dr. Batur says.
Luckily, another recent study highlights the rarity of such migration events. It identified 38 cases of migration from 2006 to 2015 in the United States. Locations for the migration in that study included vasculature other than the lung/pulmonary artery (14), axilla (11), lung/pulmonary artery (9), clavicle/shoulder (3) and chest wall (1). Overall, the study found that migration only happens to about one patient in every 1 million, although Dr. Batur says that may be an underestimate, given that all cases of migration may not be reported to the FDA.
While a migrated implant can cause pain and other location-specific complications, such as shortness of breath when it lodges in the lungs, many cases of migration are asymptomatic and are only discovered when a patient comes in for routine checkup or evaluation of another problem, Dr. Batur says.
Providers should check at every visit
Healthcare providers should check on the status of an implant each time a patient is seen. When an implant has been inserted properly, it should be easily palpated in the arm. When it cannot be located, follow-up is essential, she says.
Locating these devices is easier today than in the past, as most U.S. patients will have a newer implant (Nexplanon®), which contain 15 mg of barium to make it radiopaque. However, some patients might still have the older version, nonradiopaque Implanon®, especially if they received their device overseas. In that case, magnetic resonance imaging may be required to find it, Dr. Batur notes.
If a provider cannot feel the implant, they should never “dig” into a patient’s arm in search of it, Dr. Batur cautions. It is rarely effective and can leave unsightly scars. “Don’t let this escalate into a bigger problem than it needs to be,” she says.
When removal is needed
Once the device is located, removal is typically best accomplished by working with an interventional radiologist who has experience with this problem, she says.
If you do not have such a person in your referral base, she suggests asking the manufacturer (Merck & Co. Inc.) for assistance. The company maintains a list of centers that can help.
“You want to get the patient to the right person,” she adds.
In some very rare cases, the patient may need surgery to remove the implant, such as if the device has become lodged into an artery and endothelialized. There are times when a patient may choose to avoid surgery to remove it.
“Since we know the implants can be effective at least two years beyond their typical three-year lifespan, leaving it in can render a woman infertile. It can also cause a bleeding abnormality,” she says, adding, “This is why early detection of migration is so important.”
Dr. Batur says that since migration is often the result of improper insertion technique, providers should be sure to avoid inserting the implant into the sulcus between the bicep and tricep, and confirm that it is easily palpable immediately postinsertion.
They should also educate patients on the risks associated with insertion, even though these are rare events.
“Implants are very effective and very well-tolerated contraceptive methods that provide high efficacy for our patients for years at a time, so providers shouldn’t be afraid to use them,” she concludes. “However, they need to be aware of the potential for migration and have a plan to manage the rare case that they may see.”