K55.33 Stage 3 necrotizing enterocolitis

The ICD-10-CM code for Stage 3 necrotizing enterocolitis is K55.33 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

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

Section

K55-K64: Other diseases of intestines (K55-K64)

Category K55

37 codes (27 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to K55.33:

• Enterocolitis › necrotizing › in non-newborn › stage 3 (with pneumatosis, with perforation)
• Enterocolitis › necrotizing › with › perforation
• Enterocolitis › necrotizing › with › pneumatosis › and perforation

Inclusion Terms

• Necrotizing enterocolitis with perforation
• Necrotizing enterocolitis with pneumatosis and perforation

U.S. Hospital Utilization

• An estimated 205 U.S. inpatient stays in 2023 included K55.33 among the documented diagnoses.
• 60 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)