K55.32 ICD-10-CM Code: Stage 2 necrotizing enterocolitis

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for K55.32 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on K55.32 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for K55.32

MedCoder structured workflow — derived from this code’s own official record

Before you code K55.32

1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with K55.32. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the documentation support a condition named in K55.32’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

   ReviewP77

Consider K55.32. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Stage

The documented stage decides the sibling code; where a Use Additional Code note asks for a stage code, report it as well.

Official instructions as workflow

• Excludes1 — check before selecting K55.32(1 note)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with K55.32: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareP77

  See the official tabular notes · Guidelines I.A.12.a

• Excludes2 — not part of K55.32(2 notes)

  Coding workflow: The conditions named in this note are not included in K55.32. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  CompareA04.7, K31.81

  See the official tabular notes · Guidelines I.A.12.b

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (2)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Enterocolitis, necrotizing, in non-newborn, stage 2 (with pneumatosis, without perforation)
• Enterocolitis, necrotizing, with, pneumatosis

Official Coding Guidelines

No excerpt in the ICD-10-CM Official Guidelines names this code specifically. Its chapter carries only this chapter-wide note:

Don’t confuse K55.32 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of K55.32 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• P77— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of necrotizing enterocolitis of newborn moves the case to P77; the two are not reported together unless documented as unrelated.

  Full comparison: K55.32 vs P77 →

• K55.30— Specificity relationship (Review)

  Overlapping diagnoses in the same category.

  Overlapping codes in the same category — the documentation decides which is the more specific fit.

  What moves you there: A record that documents no more than “Necrotizing enterocolitis, unspecified” takes K55.30; specificity in the record moves it back here.

  Full comparison: K55.32 vs K55.30 →

• A04.7— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of necrotizing enterocolitis due to Clostridium difficile adds A04.7; it is not part of this code and both may be reported when both are documented.

  Full comparison: K55.32 vs A04.7 →

• K31.81— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of angioectasia (angiodysplasia) duodenum adds K31.81; it is not part of this code and both may be reported when both are documented.

  Full comparison: K55.32 vs K31.81 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• MCC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: MCC — Major Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 23 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 5 MS-DRGs: DRG 393 (MDC 06), DRG 394 (MDC 06), DRG 395 (MDC 06), DRG 791 (MDC 15), DRG 793 (MDC 15).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):DIG025 — Other specified and unspecified gastrointestinal disorders (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as MCC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

K55.019 — Acute (reversible) ischemia of small intestine, extent unspecified, K55.021 — Focal (segmental) acute infarction of small intestine, K55.022 — Diffuse acute infarction of small intestine, K55.029 — Acute infarction of small intestine, extent unspecified, K55.031 — Focal (segmental) acute (reversible) ischemia of large intestine, K55.032 — Diffuse acute (reversible) ischemia of large intestine, K55.039 — Acute (reversible) ischemia of large intestine, extent unspecified, K55.041 — Focal (segmental) acute infarction of large intestine, K55.042 — Diffuse acute infarction of large intestine, K55.049 — Acute infarction of large intestine, extent unspecified, K55.051 — Focal (segmental) acute (reversible) ischemia of intestine, part unspecified, K55.052 — Diffuse acute (reversible) ischemia of intestine, part unspecified, K55.059 — Acute (reversible) ischemia of intestine, part and extent unspecified, K55.061 — Focal (segmental) acute infarction of intestine, part unspecified, K55.062 — Diffuse acute infarction of intestine, part unspecified, K55.069 — Acute infarction of intestine, part and extent unspecified, K55.1 — Chronic vascular disorders of intestine, K55.30 — Necrotizing enterocolitis, unspecified, K55.31 — Stage 1 necrotizing enterocolitis, K55.33 — Stage 3 necrotizing enterocolitis, +2 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Other specified and unspecified gastrointestinal disorders).

K55.052 — Diffuse acute (reversible) ischemia of intestine, part unspecified, K55.059 — Acute (reversible) ischemia of intestine, part and extent unspecified, K55.061 — Focal (segmental) acute infarction of intestine, part unspecified, K55.062 — Diffuse acute infarction of intestine, part unspecified, K55.069 — Acute infarction of intestine, part and extent unspecified, K55.1 — Chronic vascular disorders of intestine, K55.20 — Angiodysplasia of colon without hemorrhage, K55.21 — Angiodysplasia of colon with hemorrhage, K55.30 — Necrotizing enterocolitis, unspecified, K55.31 — Stage 1 necrotizing enterocolitis, K55.33 — Stage 3 necrotizing enterocolitis, K55.8 — Other vascular disorders of intestine, K55.9 — Vascular disorder of intestine, unspecified, K58.0 — Irritable bowel syndrome with diarrhea, K58.1 — Irritable bowel syndrome with constipation, K58.2 — Mixed irritable bowel syndrome, K58.8 — Other irritable bowel syndrome, K58.9 — Irritable bowel syndrome, unspecified, K59.00 — Constipation, unspecified, K59.01 — Slow transit constipation, +64 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Enterocolitis”; these codes share that main term but sit in a different category of the Tabular List.

A04.71 — Enterocolitis due to Clostridium difficile, recurrent (pseudomembranous, recurrent), A04.72 — Enterocolitis due to Clostridium difficile, not specified as recurrent (pseudomembranous, not specified as recurrent), A09 — Infectious gastroenteritis and colitis, unspecified (infectious NEC), K52.0 — Gastroenteritis and colitis due to radiation (radiation), K52.9 — Noninfective gastroenteritis and colitis, unspecified, P77.1 — Stage 1 necrotizing enterocolitis in newborn (necrotizing, in newborn, stage 1), P77.2 — Stage 2 necrotizing enterocolitis in newborn (necrotizing, in newborn, stage 2), P77.3 — Stage 3 necrotizing enterocolitis in newborn (necrotizing, in newborn, stage 3), P77.9 — Necrotizing enterocolitis in newborn, unspecified (necrotizing, in newborn)

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Fecal Occult Blood Test (FOBT), Gamma-glutamyl Transferase (GGT) Test, Iron Panel, Partial Thromboplastin Time (PTT) Test, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of K55.32 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Hierarchy

• K00-K95 — Chapter 11: Diseases of the Digestive System (K00-K95) (K00-K95)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K55-K64 — Other diseases of intestines[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Clinical classification (CCSR)

• DIG025 — Other specified and unspecified gastrointestinal disorders[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• MCC — Major Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (MCC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 393 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITH MCC[MS-DRG]: “OTHER DIGESTIVE SYSTEM DIAGNOSES WITH MCC (MDC 06)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 394 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITH CC[MS-DRG]: “OTHER DIGESTIVE SYSTEM DIAGNOSES WITH CC (MDC 06)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 395 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITHOUT CC/MCC[MS-DRG]: “OTHER DIGESTIVE SYSTEM DIAGNOSES WITHOUT CC/MCC (MDC 06)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 791 — PREMATURITY WITH MAJOR PROBLEMS[MS-DRG]: “PREMATURITY WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS[MS-DRG]: “FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 06 — Diseases and Disorders of the Digestive System[MDC crossing]: “Diseases and Disorders of the Digestive System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 5,744 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026
• MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Enterocolitis, necrotizing, in non-newborn, stage 2 (with pneumatosis, without perforation)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Enterocolitis, necrotizing, with, pneumatosis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (36)

• K55 — Vascular disorders of intestine[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K55.0 — Acute vascular disorders of intestine[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K55.01 — Acute (reversible) ischemia of small intestine[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K55.011 — Focal (segmental) acute (reversible) ischemia of small intestine[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K55.012 — Diffuse acute (reversible) ischemia of small intestine[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K55.019 — Acute (reversible) ischemia of small intestine, extent unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K55.02 — Acute infarction of small intestine[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• K55.021 — Focal (segmental) acute infarction of small intestine[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 28 more

Change history

• FY2017 — Added to the code set[Change history]— CMS release files (code change ledger) · icd10cm-fy2017

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Coding guidelines Official source data

ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to K55.32 in its code family, with their registry titles.

• K55.1 — Chronic vascular disorders of intestine
• K55.2 — Angiodysplasia of colon
• K55.20 — Angiodysplasia of colon without hemorrhage
• K55.21 — Angiodysplasia of colon with hemorrhage
• K55.3 — Necrotizing enterocolitis
• K55.30 — Necrotizing enterocolitis, unspecified
• K55.31 — Stage 1 necrotizing enterocolitis
• K55.33 — Stage 3 necrotizing enterocolitis
• K55.8 — Other vascular disorders of intestine
• K55.9 — Vascular disorder of intestine, unspecified

View all codes in the K55 family