ICD-10 Code G56.21 – Lesion of ulnar nerve, right upper limb (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G56.21 – Lesion of ulnar nerve, right upper limb
What it is
G56.21 identifies a disorder of the ulnar nerve affecting the right upper limb. Use it when documentation specifies a lesion, neuropathy, or entrapment involving the right ulnar nerve.
Clinical signs
Typical findings may include numbness, tingling, or pain along the ulnar distribution of the hand and forearm. Weak grip, hand clumsiness, or intrinsic muscle weakness may also be documented; clinical features vary, refer to documentation.
When to use this code
Use this code when the provider documents a right-sided ulnar nerve lesion without a more specific diagnosis. It is appropriate for conditions such as ulnar neuropathy or entrapment at the elbow or wrist when the right side is specified. If the record only says “ulnar nerve problem,” check documentation for laterality and specificity.
Do not use for
Do not use G56.21 for left-sided or bilateral ulnar nerve disease. Do not apply it when the chart identifies a different nerve, a generalized peripheral neuropathy, or another confirmed cause; check documentation.
Coding tip
Always verify that the note states “right” upper limb and that the diagnosis is ulnar nerve lesion rather than a broader neuropathy.