2026 ICD-10-CM Diagnosis Code K31.9Disease of stomach and duodenum, unspecified
ICD-10-CM Codes›K00–K95›K20-K31›K31
- Billable — Valid for Submission
- Not Chronic
K31.9 is a billable ICD-10-CM diagnosis code for disease of stomach and duodenum, 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. 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.
- Disorder of duodenum
- Disorder of stomach
- Erosive duodenopathy
- Erosive gastropathy
- Gastric dysplasia
- Gastric mucosal lesion
- Gastritis medicamentosa
- Gastroduodenal disorder
- Hypertrophic gastropathy
- Lesion of stomach
- Mild stomach dysplasia
- Moderate stomach dysplasia
- NSAID-associated gastropathy
- Papulous gastropathy
- Reactive gastropathy
- Severe stomach dysplasia
- Stomach problem
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Disease, diseased See Also: Syndrome;
Disorder (of) See Also: Disease;
gastric (functional) K31.9
Disturbance (s) See Also: Disease;
stomach (functional) K31.9
pylorus K31.9
Gastropathy K31.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Gastric Dysplasia
a morphologic finding indicating the presence of dysplastic changes within the gastric mucosal epithelial cells.Indefinite for Gastric Dysplasia|Indefinite for Gastric Intraepithelial Neoplasia
a term used to describe an ambiguous morphologic pattern in the gastric mucosa, when there is doubt whether the findings represent a non-neoplastic or neoplastic pathologic process.Negative for Gastric Dysplasia|Negative for Gastric Intraepithelial Neoplasia
a morphologic finding indicating the absence of dysplastic changes in the gastric mucosal epithelium. it includes non-neoplastic inflammatory, reactive, or metaplastic pathologic processes.
Patient EducationClinical
Stomach Disorders
Your stomach is an organ between your esophagus and small intestine. It is where digestion of protein begins. The stomach has three tasks. It stores swallowed food. It mixes the food with stomach acids. Then it sends the mixture on to the small intestine.
Read the full article at MedlinePlus
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Convert K31.9 to ICD-9-CMHistory
Code HistoryHistory
Questions About K31.9Overview
What is the ICD-10 code for disease of stomach and duodenum, unspecified?
The ICD-10-CM code for disease of stomach and duodenum, unspecified is K31.9 (sometimes written as K319). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is K31.9 (Other diseases of stomach and duodenum) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report disease of stomach and duodenum, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does K31.9 group to?
When disease of stomach and duodenum, 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.
What is the ICD-9 equivalent of K31.9?
Under the General Equivalence Mappings, disease of stomach and duodenum, unspecified converts to ICD-9-CM 536.9 (stomach function dis NOS) and 537.9 (gastroduodenal dis NOS). The mapping is approximate, so confirm the match fits the documentation.
