K31.9 Disease of stomach and duodenum, unspecified

The ICD-10-CM code for Disease of stomach and duodenum, unspecified is K31.9 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

11: Diseases of the digestive system (K00-K95)

Section

K20-K31: Diseases of esophagus, stomach and duodenum (K20-K31)

Category K31

31 codes (25 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to K31.9:

• Gastropathy
• Lesion (s) (nontraumatic) › cardia
• Dysfunction › pylorus
• Disturbance (s) › stomach (functional)
• Disorder (of) › gastric (functional)
• Disease, diseased › stomach
• Disease, diseased › duodenum
• Lesion (s) (nontraumatic) › duodenum

U.S. Hospital Utilization

• An estimated 25,245 U.S. inpatient stays in 2023 included K31.9 among the documented diagnoses.
• 745 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Chapter 11 reserved for future expansion

11. Chapter 11: Diseases of the Digestive System (K00-K95) Reserved for future guideline expansion

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)