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G56.20 ICD-10-CM Code: Lesion of ulnar nerve, unspecified upper limb

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
6 Excludes1

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 073 — CRANIAL AND PERIPHERAL NERVE DISORDERS WITH MCC (MDC 01)
  • MS-DRG 074 — CRANIAL AND PERIPHERAL NERVE DISORDERS WITHOUT MCC (MDC 01)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for G56.20 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on G56.20 itself; “inherited from” names the category or block whose note applies here.

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Coder workflow for G56.20

MedCoder structured workflow — derived from this code’s own official record

Before you code G56.20

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, G56.20 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewG56.21, G56.22, G56.23

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

  2. Laterality is coded in this family. Confirm the side documented — right, left, or bilateral — and select the matching code (this page’s code: unspecified). The unspecified-side code applies only when the record states no side. Laterality is assigned from the documented side; where a bilateral code exists and both sides are documented, it is used instead of two unilateral codes (Guidelines I.B.13).

    ReviewG56.21 · right, G56.22 · left

    Guide: Laterality coding →

  3. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with G56.20. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — G56.20 is appropriate when the documentation goes no further.

    ReviewG56.21, G56.22, G56.23

  2. Does the documentation support a condition named in G56.20’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewM79.2, O26.82, M54.1

  3. Is the side documented?
    Yes → Select the code for the documented side (or the bilateral code when both sides are documented and one exists).
    No → Use the unspecified-side code only when the record states no side; a query is the alternative.

    ReviewG56.21 · right, G56.22 · left

Consider G56.20. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Laterality
Right, left or bilateral as documented; unspecified only when the record states no side (Guidelines I.B.13).
Any detail beyond this code’s title
What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes1 — check before selecting G56.20(6 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with G56.20: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareM79.2, O26.82, M54.1

    See the official tabular notes · Guidelines I.A.12.a

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewG56.21, G56.22, G56.23

Documentation: Both the condition G56.20 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewM79.2, O26.82, M54.1

Documentation: The record documents the condition on one side only.

Coding question: Which code in this family applies?

Path: Select the sibling code for the documented side.

Reason: Laterality is assigned from the documented side; the unspecified-side code is for records that state no side (Guidelines I.B.13).

ReviewG56.21 · right, G56.22 · left

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse G56.20 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of G56.20 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • M79.2— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of neuralgia NOS moves the case to M79.2; the two are not reported together unless documented as unrelated.

    Full comparison: G56.20 vs M79.2 →

  • O26.82— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of peripheral neuritis in pregnancy moves the case to O26.82; the two are not reported together unless documented as unrelated.

    Full comparison: G56.20 vs O26.82 →

  • M54.1— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of radiculitis NOS moves the case to M54.1; the two are not reported together unless documented as unrelated.

    Full comparison: G56.20 vs M54.1 →

  • G56.21— Laterality relationship (Review)

    Same condition; these differ only in which side is documented.

    The same condition on the other side; the documented side decides, and a bilateral code, where one exists, replaces the pair when both sides are documented.

    What moves you there: A documented right side moves the case to G56.21.

    Full comparison: G56.20 vs G56.21 →

  • G56.22— Laterality relationship (Review)

    Same condition; these differ only in which side is documented.

    The same condition on the other side; the documented side decides, and a bilateral code, where one exists, replaces the pair when both sides are documented.

    What moves you there: A documented left side moves the case to G56.22.

    Full comparison: G56.20 vs G56.22 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Code Overview

Lesion of ulnar nerve, unspecified upper limb is a billable ICD-10-CM diagnosis code (G56.20).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name G56.20 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: M79.2 — Neuralgia and neuritis, unspecified (via G56.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 2 MS-DRGs: DRG 073 (MDC 01), DRG 074 (MDC 01).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):NVS017 — Nerve and nerve root disorders (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same condition, opposite side

Same category and title, differing only in which side of the body is affected.

G56.21 — Lesion of ulnar nerve, right upper limb (right)Compare G56.20 vs G56.21 →, G56.22 — Lesion of ulnar nerve, left upper limb (left)Compare G56.20 vs G56.22 →

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Nerve and nerve root disorders).

G54.9 — Nerve root and plexus disorder, unspecified, G55 — Nerve root and plexus compressions in diseases classified elsewhere, G56.00 — Carpal tunnel syndrome, unspecified upper limb, G56.01 — Carpal tunnel syndrome, right upper limb, G56.02 — Carpal tunnel syndrome, left upper limb, G56.03 — Carpal tunnel syndrome, bilateral upper limbs, G56.10 — Other lesions of median nerve, unspecified upper limb, G56.11 — Other lesions of median nerve, right upper limb, G56.12 — Other lesions of median nerve, left upper limb, G56.13 — Other lesions of median nerve, bilateral upper limbs, G56.21 — Lesion of ulnar nerve, right upper limb, G56.22 — Lesion of ulnar nerve, left upper limb, G56.23 — Lesion of ulnar nerve, bilateral upper limbs, G56.30 — Lesion of radial nerve, unspecified upper limb, G56.31 — Lesion of radial nerve, right upper limb, G56.32 — Lesion of radial nerve, left upper limb, G56.33 — Lesion of radial nerve, bilateral upper limbs, G56.40 — Causalgia of unspecified upper limb, G56.41 — Causalgia of right upper limb, G56.42 — Causalgia of left upper limb, +94 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Lesion”, “Mononeuritis”, “Palsy”, …; these codes share that main term but sit in a different category of the Tabular List.

G52.2 — Disorders of vagus nerve (vagus nerve), G52.3 — Disorders of hypoglossal nerve (cranial nerve, twelfth), G52.7 — Disorders of multiple cranial nerves (cranial nerve, multiple), G52.8 — Disorders of other specified cranial nerves (trapezius), G52.9 — Cranial nerve disorder, unspecified (cranial nerve), G54.0 — Brachial plexus disorders (brachial plexus), G54.1 — Lumbosacral plexus disorders (lumbosacral, plexus), G54.2 — Cervical root disorders, not elsewhere classified (cervicalroot NEC), G54.3 — Thoracic root disorders, not elsewhere classified (thoracic root NEC), G54.4 — Lumbosacral root disorders, not elsewhere classified (lumbosacral, root NEC), G57.0 — Lesion of sciatic nerve (sciatic nerve), G57.1 — Meralgia paresthetica (lateral, cutaneous nerve of thigh), G57.2 — Lesion of femoral nerve (nerve, femoral), G57.3 — Lesion of lateral popliteal nerve (peroneal nerve), G57.4 — Lesion of medial popliteal nerve (tibial nerve), G57.5 — Tarsal tunnel syndrome (posterior tibial nerve), G57.6 — Lesion of plantar nerve (nerve, plantar), G57.8 — Other specified mononeuropathies of lower limb (obturator nerve), G57.9 — Unspecified mononeuropathy of lower limb (lower limb), G58.0 — Intercostal neuropathy (intercostal), +204 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

HIV Screening Test

Contextual Map

Every relationship of G56.20 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run G56.20 with this related code in Claim Check

Hierarchy

Referenced by Excludes1 notes

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 01 — Diseases and Disorders of the Nervous System[MDC crossing]: “Diseases and Disorders of the Nervous System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 8,919 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Nearest codes (35)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "G56.20 — Lesion of ulnar nerve, unspecified upper limb." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/g56.20-lesion-of-ulnar-nerve-unspecified-upper-limb

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Lesion of ulnar nerve, unspecified upper limb

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to G56.20 in its code family, with their registry titles.

View all codes in the G56 family