2026 ICD-10-CM Diagnosis Code K31.A0Gastric intestinal metaplasia, unspecified
ICD-10-CM Codes›K00–K95›K20-K31›K31
- Billable — Valid for Submission
- Not Chronic
K31.A0 is a billable ICD-10-CM diagnosis code for gastric intestinal metaplasia, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 391 through 392. Coders also document this condition as gastric intestinal metaplasia. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified disorders of stomach and duodenum.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Gastric intestinal metaplasia
- Intestinal metaplasia of pylorus of stomach
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Gastric intestinal metaplasia indefinite for dysplasia
- Gastric intestinal metaplasia NOS
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
- gastric intestinal - K31.A0
- indefinite for dysplasia - K31.A0
External Cause of Injuries IndexGuidance
References for this code in the External Cause of Injuries Index.
- Metaplasia
- gastric intestinal
- Metaplasia
- gastric intestinal
- indefinite for dysplasia
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Gastric Intestinal Metaplasia
a morphologic finding indicating the replacement of part of the gastric mucosal epithelium with intestinal-type epithelium. using immunohistochemical staining, gastric intestinal metaplasia is classified as complete or incomplete. complete intestinal metaplasia is defined by the decreased expression of gastric mucins and expression of the intestinal mucin muc2. incomplete intestinal metaplasia is defined by the co-expression of both gastric mucins and muc2.Intestinal Metaplasia of Gastric Mucosa|Gastric Intestinal Metaplasia
a morphologic finding indicating the replacement of part of the gastric mucosal epithelium with intestinal-type epithelium. using immunohistochemical staining, gastric intestinal metaplasia is classified as complete or incomplete. complete intestinal metaplasia is defined by the decreased expression of gastric mucins and expression of the intestinal mucin muc2. incomplete intestinal metaplasia is defined by the co-expression of both gastric mucins and muc2.
Code History & ChangesHistory
Replacement K31.A0 replaces the following previously assigned code(s):
- K31.89 - Other diseases of stomach and duodenum
Questions About K31.A0Overview
Is K31.A0 (Gastric intestinal metaplasia) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report gastric intestinal metaplasia, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does K31.A0 group to?
When gastric intestinal metaplasia, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 391, 392, with relative weights from 0.7796 to 1.2683 depending on complications. Higher weights mean higher Medicare reimbursement.
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.
