K51.313 Ulcerative (chronic) rectosigmoiditis with fistula

The ICD-10-CM code for Ulcerative (chronic) rectosigmoiditis with fistula is K51.313 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

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

Section

K50-K52: Noninfective enteritis and colitis (K50-K52)

Category K51

64 codes (49 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to K51.313:

• Rectosigmoiditis › ulcerative (chronic) › with › complication › fistula

U.S. Hospital Utilization

• An estimated 90 U.S. inpatient stays in 2023 included K51.313 among the documented diagnoses.

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)