Nexplanon Insertion Site on the Arm
Nexplanon should be inserted subdermally on the inner side of the non-dominant upper arm, overlying the triceps muscle, 8-10 cm (3-4 inches) from the medial epicondyle of the humerus and 3-5 cm (1.25-2 inches) posterior to (below) the sulcus (groove) between the biceps and triceps muscles. 1
Precise Anatomical Location
The FDA-approved insertion site is specifically designed to avoid major neurovascular structures:
- Distance from medial epicondyle: 8-10 cm (3-4 inches) proximally 1
- Distance from bicipital sulcus: 3-5 cm (1.25-2 inches) posterior/below 1
- Muscle location: Overlying the triceps muscle (not the biceps) 1
- Arm selection: Non-dominant upper arm 1
- Depth: Subdermally, just under the skin—NOT intramuscular or intrafascial 1
Critical Rationale for This Location
This specific anatomical site minimizes risk of neurovascular injury because major structures are concentrated in and around the bicipital sulcus:
- Anatomical studies confirm that no major neurovascular structures are located 3-5 cm posterior to the sulcus overlying the triceps 2
- The basilic vein, medial brachial cutaneous nerve, ulnar nerve, and medial antebrachial cutaneous nerve are commonly found closer to the sulcus and biceps area 2
- Positioning the arm with elbow flexion (hand underneath the head) during insertion displaces the ulnar nerve anteriorly toward the sulcus, further away from the insertion site 2
Dangers of Improper Insertion
Deep insertion (intramuscular or intrafascial) is the most serious complication and can result in:
- Neural injury causing paresthesia, with documented cases of acute ulnar neuropathy requiring surgical removal 1, 3, 4
- Vascular injury including intravascular insertion 1
- Implant migration within the arm or even to the pulmonary artery, potentially requiring endovascular or surgical procedures 1, 5
- Difficult or impossible removal, necessitating referral to upper extremity surgeons 1, 3
Subfascial placement has been documented in multiple case series requiring surgical removal by upper extremity specialists, with implants found in the subfascial plane or intramuscularly 3.
Verification After Insertion
Immediate palpation after insertion is mandatory to confirm proper subdermal placement 1:
- The implant must be palpable immediately after insertion 1
- Failure to confirm palpability may indicate non-insertion or deep insertion 1
- If the implant cannot be palpated at any time, it should be localized (via ultrasound or X-ray) and removal is recommended 1
Alternative Sites (Investigational)
While the standard arm site remains the only FDA-approved location, research has explored alternative sites:
- Scapular insertion (over the inferior edge of the scapula) demonstrated similar pharmacokinetics over 1 year in a pilot study 6
- Thigh insertion has been described in case reports for patients with arteriovenous fistulas requiring hemodialysis 7
These alternative sites are not FDA-approved and should only be considered in exceptional circumstances where standard arm insertion is contraindicated 7, 6.
REMS Program Requirement
Nexplanon is only available through a restricted REMS program due to the risk of complications from improper insertion and removal 1. All healthcare professionals must receive formal instruction and training before performing insertion or removal procedures 1.