2026 ICD-10-CM Diagnosis Code K55.30Necrotizing enterocolitis, unspecified

ICD-10-CM Codes›K00–K95›K55-K64›K55

ICD-10-CM K55.30
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K55.30 is a billable ICD-10-CM diagnosis code for necrotizing enterocolitis, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 393 through 395. Coders also document this condition as adult necrotizing enterocolitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified gastrointestinal disorders.

Code Identity

ICD-10-CM Code
K55.30
Billable Status
Yes — Valid for Submission
Code Describes
Necrotizing enterocolitis, unspecified
Short Description
Necrotizing enterocolitis, unspecified
Same as the full description in the CMS dataset.
Parent Code
K55.3
Necrotizing enterocolitis

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK55-K64Other diseases of intestines
CategoryK55Vascular disorders of intestine
This CodeK55.30Necrotizing enterocolitis, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adult necrotizing enterocolitis
  • Radiation induced enteritis of small intestine

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Necrotizing enterocolitis, NOS

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Enterocolitis
      • necrotizing
    • Enterocolitis
      • necrotizing
        • in non-newborn

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR DIG025
Other specified and unspecified gastrointestinal disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Convert K55.30 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
557.0 Ac vasc insuff intestine
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement K55.30 replaces the following previously assigned code(s):

  • K55.8 - Other vascular disorders of intestine
FY 2018AddedAdded to the ICD-10-CM code setEffective October 1, 2017.
FY 2019–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K55.30Overview

Is K55.30 (Necrotizing enterocolitis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report necrotizing enterocolitis, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K55.30 group to?

When necrotizing enterocolitis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 393, 394, 395, with relative weights from 0.6490 to 1.5993 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K55.30?

Under the General Equivalence Mappings, necrotizing enterocolitis, unspecified converts to ICD-9-CM 557.0 (ac vasc insuff intestine). The mapping is approximate, so confirm the match fits the documentation.

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.