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K26.1 ICD-10-CM Code: Acute duodenal ulcer with perforation

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

Coding at a Glance

Tabular directives
3 inclusion terms · 1 Excludes1 · 1 Excludes2 · 2 use-additional codes
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 33

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 380 — COMPLICATED PEPTIC ULCER WITH MCC (MDC 06)
  • MS-DRG 381 — COMPLICATED PEPTIC ULCER WITH CC (MDC 06)
  • MS-DRG 382 — COMPLICATED PEPTIC ULCER WITHOUT CC/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.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 78 — Intestinal Obstruction/Perforation

Other models: CMS-HCC V22 HCC 33

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for K26.1 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 K26.1 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.

  • erosion (acute) of duodenum
  • duodenum ulcer (peptic)
  • postpyloric ulcer (peptic)

Source: inherited from K26

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).

Source: inherited from K26

Excludes2 — Not Included Here

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

Source: inherited from K20-K31

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code to identify:
  • alcohol abuse and dependence (F10.-)

Source: inherited from K26

Coder workflow for K26.1

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

Before you code K26.1

  1. K26.1’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 →

  2. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with K26.1. 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 K26.1’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.

    ReviewK27

Consider K26.1. 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).
Acuity
Acute or chronic as documented; when both are documented and separate codes exist, both are reported with the acute code first (Guidelines I.B.8).
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 K26.1(1 note)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with K26.1: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareK27

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

  • Excludes2 — not part of K26.1(1 note)

    Coding workflow: The conditions named in this note are not included in K26.1. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareK44

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

  • Use Additional Code — after identifying K26.1(2 notes)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with K26.1 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    ReviewF10

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

Coding decision scenarios

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

Documentation: Both the condition K26.1 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).

ReviewK27

Documentation: Only one of the components this code’s title joins is documented.

Coding question: Is K26.1 supported?

Path: Review the code for the documented component on its own.

Reason: A combination code is assigned only when it fully identifies the documented conditions; otherwise the documented component takes its own code (Guidelines I.B.9).

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with K26.1?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

ReviewF10

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 K26.1 with…

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

The codes most likely to be picked instead of K26.1 — 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.

  • K27— 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 peptic ulcer NOS moves the case to K27; the two are not reported together unless documented as unrelated.

    Full comparison: K26.1 vs K27 →

  • K26.4— 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 “Chronic or unspecified duodenal ulcer with hemorrhage” takes K26.4; specificity in the record moves it back here.

    Full comparison: K26.1 vs K26.4 →

  • K44— 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 hiatus hernia adds K44; it is not part of this code and both may be reported when both are documented.

    Full comparison: K26.1 vs K44 →

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

Acute duodenal ulcer with perforation is a billable ICD-10-CM diagnosis code (K26.1).

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 (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.

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

Decision Points

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

  1. 2 Use Additional Code instructions — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
  2. 1 Excludes1 entry — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes
  3. 1 Excludes2 entry — those conditions are not part of this code and may be reported additionally when documented. See the Excludes2 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

  • MCC 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 structured relationships — computed from published CMS and AHRQ datasets

Other codes that name K26.1 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 3 Excludes1 notes: K63.1 — Perforation of intestine (nontraumatic) (via K26.-), K63.3 — Ulcer of intestine (via K26.-), K92.2 — Gastrointestinal hemorrhage, unspecified (via K26.-).

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: MCC — Major 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 76 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 3 MS-DRGs: DRG 380 (MDC 06), DRG 381 (MDC 06), DRG 382 (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):DIG005 — Gastroduodenal ulcer (default); DIG006 — Gastrointestinal and biliary perforation.

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 MCC — 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.

K25.0 — Acute gastric ulcer with hemorrhage, K25.1 — Acute gastric ulcer with perforation, K25.2 — Acute gastric ulcer with both hemorrhage and perforation, K25.3 — Acute gastric ulcer without hemorrhage or perforation, K25.4 — Chronic or unspecified gastric ulcer with hemorrhage, K25.5 — Chronic or unspecified gastric ulcer with perforation, K25.6 — Chronic or unspecified gastric ulcer with both hemorrhage and perforation, K25.7 — Chronic gastric ulcer without hemorrhage or perforation, K25.9 — Gastric ulcer, unspecified as acute or chronic, without hemorrhage or perforation, K26.0 — Acute duodenal ulcer with hemorrhage, K26.2 — Acute duodenal ulcer with both hemorrhage and perforation, K26.3 — Acute duodenal ulcer without hemorrhage or perforation, K26.4 — Chronic or unspecified duodenal ulcer with hemorrhage, K26.5 — Chronic or unspecified duodenal ulcer with perforation, K26.6 — Chronic or unspecified duodenal ulcer with both hemorrhage and perforation, K26.7 — Chronic duodenal ulcer without hemorrhage or perforation, K26.9 — Duodenal ulcer, unspecified as acute or chronic, without hemorrhage or perforation, K27.0 — Acute peptic ulcer, site unspecified, with hemorrhage, K27.1 — Acute peptic ulcer, site unspecified, with perforation, K27.2 — Acute peptic ulcer, site unspecified, with both hemorrhage and perforation, +55 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Intestinal Obstruction/Perforation) for risk-adjusted payment.

A54.85 — Gonococcal peritonitis, K25.1 — Acute gastric ulcer with perforation, K25.2 — Acute gastric ulcer with both hemorrhage and perforation, K25.5 — Chronic or unspecified gastric ulcer with perforation, K25.6 — Chronic or unspecified gastric ulcer with both hemorrhage and perforation, K26.2 — Acute duodenal ulcer with both hemorrhage and perforation, K26.5 — Chronic or unspecified duodenal ulcer with perforation, K26.6 — Chronic or unspecified duodenal ulcer with both hemorrhage and perforation, K27.1 — Acute peptic ulcer, site unspecified, with perforation, K27.2 — Acute peptic ulcer, site unspecified, with both hemorrhage and perforation, K27.5 — Chronic or unspecified peptic ulcer, site unspecified, with perforation, K27.6 — Chronic or unspecified peptic ulcer, site unspecified, with both hemorrhage and perforation, K28.1 — Acute gastrojejunal ulcer with perforation, K28.2 — Acute gastrojejunal ulcer with both hemorrhage and perforation, K28.5 — Chronic or unspecified gastrojejunal ulcer with perforation, K28.6 — Chronic or unspecified gastrojejunal ulcer with both hemorrhage and perforation, K50.012 — Crohn's disease of small intestine with intestinal obstruction, K50.112 — Crohn's disease of large intestine with intestinal obstruction, K50.812 — Crohn's disease of both small and large intestine with intestinal obstruction, K50.912 — Crohn's disease, unspecified, with intestinal obstruction, +55 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

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (Gastroduodenal ulcer, Gastrointestinal and biliary perforation).

K22.3 — Perforation of esophagus, K25.1 — Acute gastric ulcer with perforation, K25.3 — Acute gastric ulcer without hemorrhage or perforation, K25.5 — Chronic or unspecified gastric ulcer with perforation, K25.7 — Chronic gastric ulcer without hemorrhage or perforation, K25.9 — Gastric ulcer, unspecified as acute or chronic, without hemorrhage or perforation, K26.3 — Acute duodenal ulcer without hemorrhage or perforation, K26.5 — Chronic or unspecified duodenal ulcer with perforation, K26.7 — Chronic duodenal ulcer without hemorrhage or perforation, K26.9 — Duodenal ulcer, unspecified as acute or chronic, without hemorrhage or perforation, K27.1 — Acute peptic ulcer, site unspecified, with perforation, K27.3 — Acute peptic ulcer, site unspecified, without hemorrhage or perforation, K27.5 — Chronic or unspecified peptic ulcer, site unspecified, with perforation, K27.7 — Chronic peptic ulcer, site unspecified, without hemorrhage or perforation, K27.9 — Peptic ulcer, site unspecified, unspecified as acute or chronic, without hemorrhage or perforation, K28.1 — Acute gastrojejunal ulcer with perforation, K28.3 — Acute gastrojejunal ulcer without hemorrhage or perforation, K28.5 — Chronic or unspecified gastrojejunal ulcer with perforation, K28.7 — Chronic gastrojejunal ulcer without hemorrhage or perforation, K28.9 — Gastrojejunal ulcer, unspecified as acute or chronic, without hemorrhage or perforation, +14 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), Iron Panel, Partial Thromboplastin Time (PTT) Test, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of K26.1 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 K26.1 with these 3 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 78 — Intestinal Obstruction/Perforation [CMS-HCC]— CMS-HCC V28 · 2026

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

  • Ulcer, ulcerated, ulcerating, ulceration, ulcerative, duodenum, duodenal (eroded) (peptic), acute, with, perforation[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027

Nearest codes (9)

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
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
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

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. "K26.1 — Acute duodenal ulcer with perforation." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/k26.1-acute-duodenal-ulcer-with-perforation

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Acute duodenal ulcer with perforation

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 K26.1 in its code family, with their registry titles.

View all codes in the K26 family