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M46.1 ICD-10-CM Code: Sacroiliitis, not elsewhere classified

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

Coding at a Glance

Risk adjustment
CMS-HCC V22 category 40

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 551 — MEDICAL BACK PROBLEMS WITH MCC (MDC 08)
  • MS-DRG 552 — MEDICAL BACK PROBLEMS WITHOUT MCC (MDC 08)

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.

Coder workflow for M46.1

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

Before you code M46.1

  1. “Other” (NEC) means the condition is specified in the record but no dedicated code captures it. Confirm the documented form is not one a sibling code names before settling on M46.1; if the record states no specifics at all, the unspecified sibling applies instead. “Other” codes are for documented conditions the classification gives no specific code; “unspecified” codes are for records lacking the detail (Guidelines I.A.9.a, I.A.9.b).

    ReviewM46.0, M46.2, M46.3

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

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).
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.

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 M46.1 with…

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

The codes most likely to be picked instead of M46.1 — 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.

  • M46.4— Specificity relationship (Review)

    Overlapping diagnoses in the same category.

    Overlapping codes in the same category — the documentation decides which is the more specific fit.

    What moves you there: A record that documents no more than “Discitis, unspecified” takes M46.4; specificity in the record moves it back here.

    Full comparison: M46.1 vs M46.4 →

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

Sacroiliitis, not elsewhere classified is a billable ICD-10-CM diagnosis code (M46.1).

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

Indexed Clinical Terms (4)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

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 M46.1 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: G55 — Nerve root and plexus compressions in diseases classified elsewhere (via M46.-).

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

Referenced by 7 Excludes2 notes: M20 — Acquired deformities of fingers and toes (via M46.-), M20-M25 — Other joint disorders (M20-M25) (via M46.-), M21 — Other acquired deformities of limbs (via M46.-), M22 — Disorder of patella (via M46.-), M23 — Internal derangement of knee (via M46.-), M24 — Other specific joint derangements (via M46.-), M25 — Other joint disorder, not elsewhere classified (via M46.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

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 551 (MDC 08), DRG 552 (MDC 08).

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

Clinical classification (AHRQ CCSR):MUS011 — Spondylopathies/spondyloarthropathy (including infective) (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 clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Spondylopathies/spondyloarthropathy (including infective)).

+361 more

Same Index main term, other category

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

M45.0 — Ankylosing spondylitis of multiple sites in spine (ankylosing, multiple sites), M45.1 — Ankylosing spondylitis of occipito-atlanto-axial region (ankylosing, occipito-atlanto-axial region), M45.2 — Ankylosing spondylitis of cervical region (ankylosing, cervical region), M45.3 — Ankylosing spondylitis of cervicothoracic region (ankylosing, cervicothoracic region), M45.4 — Ankylosing spondylitis of thoracic region (ankylosing, thoracic region), M45.5 — Ankylosing spondylitis of thoracolumbar region (ankylosing, thoracolumbar region), M45.6 — Ankylosing spondylitis lumbar region (ankylosing, lumbar region), M45.7 — Ankylosing spondylitis of lumbosacral region (ankylosing, lumbosacral region), M45.8 — Ankylosing spondylitis sacral and sacrococcygeal region (ankylosing, sacrococcygeal region), M45.9 — Ankylosing spondylitis of unspecified sites in spine (ankylosing), M53.3 — Sacrococcygeal disorders, not elsewhere classified (sacroiliac joint), N05.0 — Unspecified nephritic syndrome with minor glomerular abnormality (minimal), N41.8 — Other inflammatory diseases of prostate (prostate, specified type NEC), N48.29 — Other inflammatory disorders of penis (penis), N49.1 — Inflammatory disorders of spermatic cord, tunica vaginalis and vas deferens (vas deferens), N49.2 — Inflammatory disorders of scrotum (scrotum), N49.8 — Inflammatory disorders of other specified male genital organs (genital organ, male, specified NEC), N49.9 — Inflammatory disorder of unspecified male genital organ (genital organ, male), N61.0 — Mastitis without abscess (areola), N73.0 — Acute parametritis and pelvic cellulitis (parametrium), +126 more

Contextual Map

Every relationship of M46.1 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 M46.1 with these 8 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 08 — Diseases and Disorders of the Musculoskeletal System and Connective Tissue[MDC crossing]: “Diseases and Disorders of the Musculoskeletal System and Connective Tissue — 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. 18,439 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries

  • Change (s) (in) (of), inflammatory, sacroiliac[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Inflammation, inflamed, inflammatory (with exudation), joint NEC, sacroiliac[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Sacroiliitis NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Spondylitis (chronic), sacroiliac NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027

Nearest codes (40)

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. "M46.1 — Sacroiliitis, not elsewhere classified." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/m46.1-sacroiliitis-not-elsewhere-classified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Sacroiliitis, not elsewhere classified

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 M46.1 in its code family, with their registry titles.

View all codes in the M46 family