K51.518 ICD-10-CM Code: Left sided colitis with other complication

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for K51.518 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on K51.518 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for K51.518

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

Before you code K51.518

1. Laterality is coded in this family. Confirm the side documented — right, left, or bilateral — and select the matching code (this page’s code: left). 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).

   See the relationships section · Guide: Laterality coding →

2. K51.518’s title joins a condition with an associated condition or complication. Confirm each component is documented. Where the classification presumes the link through the “with” convention, only a provider statement that the conditions are unrelated defeats it. A combination code is assigned only when it fully identifies the documented conditions; a required second code for the stage, type or manifestation is still reported when the notes ask for it (Guidelines I.B.9, I.A.15).

   Guide: Combination codes →

3. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with K51.518. 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 documentation support a condition named in K51.518’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.

   ReviewK58, K59.3

2. 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.

Consider K51.518. Then work the Use Additional Code note, and 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).

The associated condition or complication

Whether the associated condition the title names is documented; the “with” convention presumes some links, and a provider statement that the conditions are unrelated defeats it (Guidelines I.A.15).

The conditions the Use Additional Code note names

Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

• Excludes1 — check before selecting K51.518(3 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with K51.518: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareK58, K59.3

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

• Use Additional Code — after identifying K51.518(6 notes)

  Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with K51.518 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

  ReviewK60.3, K60.5, K60.4, L88

  See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

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

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.

Indexed Clinical Terms (1)

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.

• Colitis (acute) (catarrhal) (chronic) (noninfective) (hemorrhagic), left sided, with, complication, specified NEC

Official Coding Guidelines

No excerpt in the ICD-10-CM Official Guidelines names this code specifically. Its chapter carries only this chapter-wide note:

Don’t confuse K51.518 with…

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

The codes most likely to be picked instead of K51.518 — 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.

• K58— 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 irritable bowel syndrome moves the case to K58; the two are not reported together unless documented as unrelated.

  Full comparison: K51.518 vs K58 →

• K59.3— 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 megacolon moves the case to K59.3; the two are not reported together unless documented as unrelated.

  Full comparison: K51.518 vs K59.3 →

• K51.519— 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 “Left sided colitis with unspecified complications” takes K51.519; specificity in the record moves it back here.

  Full comparison: K51.518 vs K51.519 →

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.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

1. Laterality is coded in this family. Confirm the documented side matches the code — the opposite-side siblings are in the relationships section. See the opposite-side sibling codes
2. 6 Use Additional Code instructions — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
3. 3 Excludes1 entries — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

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 K51.518 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 3 Excludes1 notes: K50 — Crohn's disease [regional enteritis] (via K51.-), K62.6 — Ulcer of anus and rectum (via K51.-), K63.3 — Ulcer of intestine (via K51.-).

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

Referenced by 4 Code First instructions across 2 chapters: F54 — Psychological and behavioral factors associated with disorders or diseases classified elsewhere (via K51.-), K60.3 — Anal fistula (via K51.-), K60.4 — Rectal fistula (via K51.-), K60.5 — Anorectal fistula (via K51.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

Referenced by 2 Code Also instructions: M07 — Enteropathic arthropathies (via K51.-), M08 — Juvenile arthritis (via K51.-).

These codes suggest coding this condition alongside when both are present.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 77 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 3 MS-DRGs: DRG 385 (MDC 06), DRG 386 (MDC 06), DRG 387 (MDC 06).

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

Clinical classification (AHRQ CCSR):DIG011 — Regional enteritis and ulcerative colitis (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 process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

K51.412 — Inflammatory polyps of colon with intestinal obstruction, K51.413 — Inflammatory polyps of colon with fistula, K51.414 — Inflammatory polyps of colon with abscess, K51.418 — Inflammatory polyps of colon with other complication, K51.419 — Inflammatory polyps of colon with unspecified complications, K51.50 — Left sided colitis without complications, K51.511 — Left sided colitis with rectal bleeding, K51.512 — Left sided colitis with intestinal obstruction, K51.513 — Left sided colitis with fistula, K51.514 — Left sided colitis with abscess, K51.519 — Left sided colitis with unspecified complications, K51.80 — Other ulcerative colitis without complications, K51.811 — Other ulcerative colitis with rectal bleeding, K51.812 — Other ulcerative colitis with intestinal obstruction, K51.813 — Other ulcerative colitis with fistula, K51.814 — Other ulcerative colitis with abscess, K51.818 — Other ulcerative colitis with other complication, K51.819 — Other ulcerative colitis with unspecified complications, K51.90 — Ulcerative colitis, unspecified, without complications, K51.911 — Ulcerative colitis, unspecified with rectal bleeding, +56 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Ulcerative Colitis) for risk-adjusted payment.

K51.412 — Inflammatory polyps of colon with intestinal obstruction, K51.413 — Inflammatory polyps of colon with fistula, K51.414 — Inflammatory polyps of colon with abscess, K51.418 — Inflammatory polyps of colon with other complication, K51.419 — Inflammatory polyps of colon with unspecified complications, K51.50 — Left sided colitis without complications, K51.511 — Left sided colitis with rectal bleeding, K51.512 — Left sided colitis with intestinal obstruction, K51.513 — Left sided colitis with fistula, K51.514 — Left sided colitis with abscess, K51.519 — Left sided colitis with unspecified complications, K51.80 — Other ulcerative colitis without complications, K51.811 — Other ulcerative colitis with rectal bleeding, K51.812 — Other ulcerative colitis with intestinal obstruction, K51.813 — Other ulcerative colitis with fistula, K51.814 — Other ulcerative colitis with abscess, K51.818 — Other ulcerative colitis with other complication, K51.819 — Other ulcerative colitis with unspecified complications, K51.90 — Ulcerative colitis, unspecified, without complications, K51.911 — Ulcerative colitis, unspecified with rectal bleeding, +28 more

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Intestine Transplant Status/Complications, Crohn's Disease (Regional Enteritis)

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Regional enteritis and ulcerative colitis).

K51.412 — Inflammatory polyps of colon with intestinal obstruction, K51.413 — Inflammatory polyps of colon with fistula, K51.414 — Inflammatory polyps of colon with abscess, K51.418 — Inflammatory polyps of colon with other complication, K51.419 — Inflammatory polyps of colon with unspecified complications, K51.50 — Left sided colitis without complications, K51.511 — Left sided colitis with rectal bleeding, K51.512 — Left sided colitis with intestinal obstruction, K51.513 — Left sided colitis with fistula, K51.514 — Left sided colitis with abscess, K51.519 — Left sided colitis with unspecified complications, K51.80 — Other ulcerative colitis without complications, K51.811 — Other ulcerative colitis with rectal bleeding, K51.812 — Other ulcerative colitis with intestinal obstruction, K51.813 — Other ulcerative colitis with fistula, K51.814 — Other ulcerative colitis with abscess, K51.818 — Other ulcerative colitis with other complication, K51.819 — Other ulcerative colitis with unspecified complications, K51.90 — Ulcerative colitis, unspecified, without complications, K51.911 — Ulcerative colitis, unspecified with rectal bleeding, +56 more

Same Index main term, other category

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

A06.2 — Amebic nondysenteric colitis (amebic, nondysenteric), A07.0 — Balantidiasis (balantidial), A07.1 — Giardiasis [lambliasis] (giardial), A07.3 — Isosporiasis (coccidial), A07.8 — Other specified protozoal intestinal diseases (trichomonal), A07.9 — Protozoal intestinal disease, unspecified (protozoal), A09 — Infectious gastroenteritis and colitis, unspecified (regional, infectious), A18.32 — Tuberculous enteritis (tuberculous), A22.2 — Gastrointestinal anthrax (anthrax), F54 — Psychological and behavioral factors associated with disorders or diseases classified elsewhere (mucous, psychogenic), K52.0 — Gastroenteritis and colitis due to radiation (due to radiation), K52.1 — Toxic gastroenteritis and colitis (toxic NEC), K52.21 — Food protein-induced enterocolitis syndrome (allergic, with, food protein-induced enterocolitis syndrome), K52.29 — Other allergic and dietetic gastroenteritis and colitis (dietetic), K52.3 — Indeterminate colitis (indeterminate, so stated), K52.82 — Eosinophilic colitis (eosinophilic), K52.831 — Collagenous colitis (collagenous), K52.832 — Lymphocytic colitis (lymphocytic), K52.838 — Other microscopic colitis (microscopic, specified NEC), K52.839 — Microscopic colitis, unspecified (microscopic), +13 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.

Fecal Occult Blood Test (FOBT), Gamma-glutamyl Transferase (GGT) Test, Iron Panel, Partial Thromboplastin Time (PTT) Test, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of K51.518 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 K51.518 with these 9 related codes in Claim Check

Hierarchy

• K00-K95 — Chapter 11: Diseases of the Digestive System (K00-K95) (K00-K95)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K50-K52 — Noninfective enteritis and colitis[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Excludes1 notes

• K50 — Crohn's disease [regional enteritis][Excludes1](via K51.-): “ulcerative colitis (K51.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K62.6 — Ulcer of anus and rectum[Excludes1](via K51.-): “ulcerative colitis (K51.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K63.3 — Ulcer of intestine[Excludes1](via K51.-): “ulcerative colitis (K51.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Code First instructions

• F54 — Psychological and behavioral factors associated with disorders or diseases classified elsewhere[Code First](via K51.-): “ulcerative colitis (K51.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K60.3 — Anal fistula[Code First](via K51.-): “ulcerative colitis (K51.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K60.4 — Rectal fistula[Code First](via K51.-): “ulcerative colitis (K51.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• K60.5 — Anorectal fistula[Code First](via K51.-): “ulcerative colitis (K51.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Code Also instructions

• M07 — Enteropathic arthropathies[Code Also](via K51.-): “ulcerative colitis (K51.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• M08 — Juvenile arthritis[Code Also](via K51.-): “ulcerative colitis (K51.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• DIG011 — Regional enteritis and ulcerative colitis[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

Risk adjustment (CMS-HCC)

• HCC 81 — Ulcerative Colitis [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 385 — INFLAMMATORY BOWEL DISEASE WITH MCC[MS-DRG]: “INFLAMMATORY BOWEL DISEASE WITH MCC (MDC 06)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 386 — INFLAMMATORY BOWEL DISEASE WITH CC[MS-DRG]: “INFLAMMATORY BOWEL DISEASE WITH CC (MDC 06)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 387 — INFLAMMATORY BOWEL DISEASE WITHOUT CC/MCC[MS-DRG]: “INFLAMMATORY BOWEL DISEASE WITHOUT CC/MCC (MDC 06)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 06 — Diseases and Disorders of the Digestive System[MDC crossing]: “Diseases and Disorders of the Digestive 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. 5,744 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Colitis (acute) (catarrhal) (chronic) (noninfective) (hemorrhagic), left sided, with, complication, specified NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (40)

• K51 — Ulcerative colitis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K51.312 — Ulcerative (chronic) rectosigmoiditis with intestinal obstruction[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K51.313 — Ulcerative (chronic) rectosigmoiditis with fistula[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K51.314 — Ulcerative (chronic) rectosigmoiditis with abscess[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K51.318 — Ulcerative (chronic) rectosigmoiditis with other complication[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K51.319 — Ulcerative (chronic) rectosigmoiditis with unspecified complications[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K51.4 — Inflammatory polyps of colon[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K51.40 — Inflammatory polyps of colon without complications[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 32 more

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 FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Coding guidelines Official source data

ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 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 — v43 Release, file and checksum · Publisher’s page

Risk adjustment Official source data

2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release 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

Nearest Codes in This Family

Official ICD-10-CM classifications closest to K51.518 in its code family, with their registry titles.

• K51.51 — Left sided colitis with complications
• K51.511 — Left sided colitis with rectal bleeding
• K51.512 — Left sided colitis with intestinal obstruction
• K51.513 — Left sided colitis with fistula
• K51.514 — Left sided colitis with abscess
• K51.519 — Left sided colitis with unspecified complications
• K51.8 — Other ulcerative colitis
• K51.80 — Other ulcerative colitis without complications
• K51.81 — Other ulcerative colitis with complications
• K51.811 — Other ulcerative colitis with rectal bleeding

View all codes in the K51 family