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K31.6 ICD-10-CM Code: Fistula of stomach and duodenum

Compare with another code for K31.6Check this code on a claim

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

Coding at a Glance

Tabular directives
3 inclusion terms · 3 Excludes2 · 1 code-also instruction

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

Code alsoMay be needed with this code
  • Code also, if applicable, disruption of internal operation (surgical) wound (T81.32-)
Excludes2Not included here; may be reported together
IncludesWhat this code covers
  • functional disorders of stomach (from K31)
  • Gastrocolic fistula
  • Gastrojejunocolic fistula

Where it sits Source: CMS/NCHS

Under:Chapter 11: Diseases of the Digestive SystemK20-K31 Diseases of esophagus, stomach and duodenumK31 Other diseases of stomach and duodenum

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

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 391 — ESOPHAGITIS, GASTROENTERITIS AND MISCELLANEOUS DIGESTIVE DISORDERS WITH MCC (MDC 06)
  • MS-DRG 392 — ESOPHAGITIS, GASTROENTERITIS AND MISCELLANEOUS DIGESTIVE DISORDERS WITHOUT MCC (MDC 06)

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 K31.6 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 K31.6 itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • functional disorders of stomach

Source: inherited from K31

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Gastrocolic fistula
  • Gastrojejunocolic fistula

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Code Also

Additional codes that may be required to fully describe the encounter.

  • Code also, if applicable, disruption of internal operation (surgical) wound (T81.32-)

Coder workflow for K31.6

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

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).

Official instructions as workflow

  • Excludes2 — not part of K31.6(3 notes)

    Coding workflow: The conditions named in this note are not included in K31.6. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareE08.43, E09.43, E10.43, E11.43, E13.43, K44

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

  • Code Also — related condition(1 note)

    Coding workflow: Review the related condition when both are documented and the instruction applies. A Code Also note does not fix sequencing; the order follows the circumstances of the encounter.

    ReviewT81.32

    See the official tabular notes · Guidelines I.A.17

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 K31.6 with…

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

The codes most likely to be picked instead of K31.6 — 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.

  • K31.9— 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 “Disease of stomach and duodenum, unspecified” takes K31.9; specificity in the record moves it back here.

    Full comparison: K31.6 vs K31.9 →

  • E08.43— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of diabetic gastroparesis adds E08.43; it is not part of this code and both may be reported when both are documented.

    Full comparison: K31.6 vs E08.43 →

  • E09.43— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of diabetic gastroparesis adds E09.43; it is not part of this code and both may be reported when both are documented.

    Full comparison: K31.6 vs E09.43 →

  • E10.43— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of diabetic gastroparesis adds E10.43; it is not part of this code and both may be reported when both are documented.

    Full comparison: K31.6 vs E10.43 →

  • E11.43— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of diabetic gastroparesis adds E11.43; it is not part of this code and both may be reported when both are documented.

    Full comparison: K31.6 vs E11.43 →

  • E13.43— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of diabetic gastroparesis adds E13.43; it is not part of this code and both may be reported when both are documented.

    Full comparison: K31.6 vs E13.43 →

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.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Fistula of stomach and duodenum is a billable ICD-10-CM diagnosis code (K31.6).

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

Official Coding Guidelines

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

Chapter 11: Diseases of the Digestive System (K00-K95)

Reserved for future guideline expansion

Verify Before Coding

  • CC as a secondary diagnosis (FY2027). 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-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name K31.6 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: K63.2 — Fistula of intestine.

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

Referenced by 1 Excludes2 note: K59 — Other functional intestinal disorders (via K31.-).

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: 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 10 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 391 (MDC 06), DRG 392 (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):DIG008 — Other specified and unspecified disorders of stomach and duodenum (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.

Q38.5 — Congenital malformations of palate, not elsewhere classified, Q40.8 — Other specified congenital malformations of upper alimentary tract, Q40.9 — Congenital malformation of upper alimentary tract, unspecified, Q43.4 — Duplication of intestine, Q43.5 — Ectopic anus, Q43.6 — Congenital fistula of rectum and anus, Q43.7 — Persistent cloaca, Q43.8 — Other specified congenital malformations of intestine, Q43.9 — Congenital malformation of intestine, unspecified

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Other specified and unspecified disorders of stomach and duodenum).

K30 — Functional dyspepsia, K31.0 — Acute dilatation of stomach, K31.1 — Adult hypertrophic pyloric stenosis, K31.2 — Hourglass stricture and stenosis of stomach, K31.3 — Pylorospasm, not elsewhere classified, K31.4 — Gastric diverticulum, K31.7 — Polyp of stomach and duodenum, K31.811 — Angiodysplasia of stomach and duodenum with bleeding, K31.819 — Angiodysplasia of stomach and duodenum without bleeding, K31.82 — Dieulafoy lesion (hemorrhagic) of stomach and duodenum, K31.83 — Achlorhydria, K31.84 — Gastroparesis, K31.89 — Other diseases of stomach and duodenum, K31.9 — Disease of stomach and duodenum, unspecified, K31.A0 — Gastric intestinal metaplasia, unspecified, K31.A11 — Gastric intestinal metaplasia without dysplasia, involving the antrum, K31.A12 — Gastric intestinal metaplasia without dysplasia, involving the body (corpus), K31.A13 — Gastric intestinal metaplasia without dysplasia, involving the fundus, K31.A14 — Gastric intestinal metaplasia without dysplasia, involving the cardia, K31.A15 — Gastric intestinal metaplasia without dysplasia, involving multiple sites, +4 more

Same Index main term, other category

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

J34.89 — Other specified disorders of nose and nasal sinuses (nose), J38.7 — Other diseases of larynx (larynx), J39.2 — Other diseases of pharynx (pharynx), J86.0 — Pyothorax with fistula (lung), J95.04 — Tracheo-esophageal fistula following tracheostomy (tracheoesophageal, following tracheostomy), K04.6 — Periapical abscess with sinus (dental), K11.4 — Fistula of salivary gland (parotid), K12.2 — Cellulitis and abscess of mouth (oral), K13.0 — Diseases of lips (lip), K22.89 — Other specified disease of esophagus (esophagus), K38.3 — Fistula of appendix (appendix, appendicular), K60.30 — Anal fistula, unspecified (in ano), K60.31 — Anal fistula, simple (anus, anal, superficial), K60.311 — Anal fistula, simple, initial (anus, anal, simple, new), K60.312 — Anal fistula, simple, persistent (anus, anal, simple, chronic), K60.313 — Anal fistula, simple, recurrent (anus, anal, simple, recurrent), K60.319 — Anal fistula, simple, unspecified (anus, anal, simple), K60.32 — Anal fistula, complex (anus, anal, extrasphincteric), K60.321 — Anal fistula, complex, initial (anus, anal, complex, new), K60.322 — Anal fistula, complex, persistent (anus, anal, complex, chronic), +114 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)

Contextual Map

Every relationship of K31.6 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 K31.6 with these 3 related codes in Claim Check

Hierarchy

Code Also

Referenced by Excludes1 notes

Referenced by Excludes2 notes

Clinical classification (CCSR)

MS-DRG Grouper

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. 5,748 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries

  • Fistula (cutaneous), duodenum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fistula (cutaneous), gastric[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fistula (cutaneous), gastrocolic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fistula (cutaneous), gastroenterocolic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fistula (cutaneous), gastroesophageal[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fistula (cutaneous), gastrojejunal[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fistula (cutaneous), gastrojejunocolic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fistula (cutaneous), stomach[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027

Nearest codes (31)

Change history

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

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Indexed Clinical Terms (8)

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.

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
Coding guidelines Official source data
ICD-10-CM Official Guidelines for Coding and Reporting (FY2027), quoted by section 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-derived 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 editorial 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.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

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. "K31.6 — Fistula of stomach and duodenum." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/k31.6-fistula-of-stomach-and-duodenum

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Fistula of stomach and duodenum

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 K31.6 in its code family, with their registry titles.

View all codes in the K31 family