2026 ICD-10-CM Diagnosis Code K26.1Acute duodenal ulcer with perforation

ICD-10-CM Codes›K00–K95›K20-K31›K26

ICD-10-CM K26.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K26.1 is a billable ICD-10-CM diagnosis code for acute duodenal ulcer with perforation. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 380 through 382. Coders also document this condition as acute duodenal ulcer with obstruction. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Gastroduodenal ulcer and Gastrointestinal and biliary perforation.

Code Identity

ICD-10-CM Code
K26.1
Billable Status
Yes — Valid for Submission
Code Describes
Acute duodenal ulcer with perforation
Short Description
Acute duodenal ulcer with perforation
Same as the full description in the CMS dataset.
Parent Code
K26
Duodenal ulcer

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK20-K31Diseases of esophagus, stomach and duodenum
CategoryK26Duodenal ulcer
This CodeK26.1Acute duodenal ulcer with perforation

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute duodenal ulcer with obstruction
  • Acute duodenal ulcer with perforation
  • Acute duodenal ulcer with perforation AND obstruction
  • Acute duodenal ulcer with perforation but without obstruction
  • Acute peptic ulcer with perforation AND obstruction
  • Duodenal ulcer with perforation AND obstruction
  • Duodenal ulcer with perforation but without obstruction

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Ulcer, ulcerated, ulcerating, ulceration, ulcerative
      • duodenum, duodenal (eroded) (peptic)
        • acute
          • with
            • perforation

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR DIG005
Gastroduodenal ulcer
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR DIG006
Gastrointestinal and biliary perforation
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Duodenal Ulcer

    a peptic ulcer located in the duodenum.

Patient EducationClinical

Peptic Ulcer

A peptic ulcer is a sore in the lining of your stomach or your duodenum, the first part of your small intestine. A burning stomach pain is the most common symptom. The pain:

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert K26.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
532.10 Ac duodenal ulcer w perf
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K26.1Overview

Is K26.1 (Duodenal ulcer) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report acute duodenal ulcer with perforation on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K26.1 group to?

When acute duodenal ulcer with perforation is the principal diagnosis on an inpatient stay, it groups to MS-DRG 380, 381, 382, with relative weights from 0.8006 to 1.9622 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K26.1?

Under the General Equivalence Mappings, acute duodenal ulcer with perforation converts to ICD-9-CM 532.10 (ac duodenal ulcer w perf). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.