These are very similar contraceptive polymer rods. One is implanted just below the skin of the inner, upper arm, and it slowly releases a contraceptive hormone, etonogesterel.
The rods are 4 cm long and 2 mm in diameter, about the size of a matchstick. This system prevents pregnancy for at least 3 years, probably longer.
The differences between these systems include packaging differences, inserter differences, and in the case of Nexplanon and Implanon NXT, they are radio opaque (Implanon is not radio opaque).
They are believed to exert their contraceptive effect by some or all of the following:
- Inhibiting ovulation
- Changing cervical mucous
- Changing the lining of the uterus
- Altering uterine contraction patterns
- Altering fallopian tube function
- Other, as yet unclassified mechanisms
- When removed, fertility returns promptly.
Effectiveness
This system has a failure rate of about 0.05% each year.
Contraindications
- Undiagnosed vaginal bleeding
- Known or suspected pregnancy
- Known or suspected breast cancer
- Active thrombophlebitis or thromboembolism
- History of idiopathic intracranial hypertension
- Benign or malignant liver tumors or other acute liver disease
- Known hypersensitivity to etonogestrel
Abnormal Bleeding
Many women using this system will experience abnormal bleeding patterns, consisting of spotting, prolonged bleeding, unpredictable onset of flow and amenorrhea, primarily in the first year of use. For some, the abnormal bleeding will persist throughout their employment of this system. While overall, the number of days of some bleeding in these women usually increases, the total amount of blood loss usually decreases, and anemia is not a problem. This side effect, abnormal bleeding, is generally tolerated and no treatment is necessary. For the woman who is quite distressed, or in whom the bleeding is clinically significant, control with BCPs is usually effective, but may alter the effectiveness of the method and theoretically could lead to an increased risk of thrombophlebitis or other hormone-related side effect. Removal of the implant may occasionally be necessary.
Weight Gain or Loss/Nausea/Depression
These have all been reported in association with this system, but it is unknown whether they occur more frequently among women using the implant or not using the implant. If the symptoms are mild, toleration will usually bring relief in time. If symptoms are severe, removal of the implant may be necessary.
Infection
Infection at the implant site is an uncommon complication, but is treated by removal of the implants, bacterial cultures and antibiotics.
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Insertion
Insertion by a qualified provider requires specific training from the manufacturer, as there are surgical complexities to the insertion that may not be obvious.
The implant is inserted in the inner, upper arm (non-dominant side), 8-10 cm above the elbow crease, just beneath the dermis.
When in place, it is typically invisible, but may be seen in extremely thin patients.
The implant usually remains in place, but occasionally may migrate. The radio opaque varieties can be identified with a simple x-ray. Otherwise, CT scan, MRI, or sometimes ultrasound can reveal it's location.
Two marks are made with a pen on the skin. One marks the insertion site, and the other several cm away (proximal) to provide orientation for insertion. After cleansing the skin with surgical disinfectant, local anesthetic is administered at the injection site, and along the planned route of the implant, just beneath the skin..
The trocar needle is inserted through the skin, allowing the implant to be inserted just subdermally and proximally. A bandaid is placed over the injection site and a small pressure dressing applied for 24 hours to reduce bruising.
Removal
After palpating the implant and surgically preparing the skin, local anesthetic is injected to allow a 2 mm skin longitudinal incision at the tip of the implant (distal end). 3 ml of anesthetic in injected beneath the distal tip of the implant. Push the implant toward the incision with your fingers and grasp it with a hemostat. Before it can be removed, you may need to open the fibrous capsule which will have developed around the implant. Open the capsule with a scalpel or another hemostat. Then grasp the implant and pull it straight out through the incision. The incision site is closed with a steri-strip and light pressure bandage for 24 hours to minimize bruising.
New implants may be inserted at the time of the removal of the old one, through the same incision site, but with additional local anesthetic along the route of the implant.
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