ICD-10 Code G57.91 – Unspecified mononeuropathy of right lower limb (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G57.91 – Unspecified mononeuropathy of right lower limb
What it is
This code identifies a single nerve disorder affecting the right lower limb when the exact nerve is not specified. It is used when documentation confirms mononeuropathy but does not name a more precise site.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include localized numbness, tingling, pain, or weakness in the right leg, with symptoms matching a peripheral nerve distribution.
When to use this code
Use G57.91 when the provider documents mononeuropathy of the right lower limb and no more specific nerve diagnosis is available. It also fits when the record says “unspecified” or the nerve involved cannot be determined from the note. Check documentation if the cause is separately reported.
Do not use for
Do not use this code for polyneuropathy, radiculopathy, or generalized neurologic symptoms without a documented single-nerve disorder. If the affected nerve is named, code the more specific mononeuropathy instead.
Coding tip
Look for laterality and whether the provider identified a specific nerve before defaulting to the unspecified code.