Skip to main content

P77.9 ICD-10-CM Code: Necrotizing enterocolitis in newborn, unspecified

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
1 inclusion term
Risk adjustment
CMS-HCC V28: 1 category

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 791 — PREMATURITY WITH MAJOR PROBLEMS (MDC 15)
  • MS-DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 78 — Intestinal Obstruction/Perforation

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for P77.9 in the official ICD-10-CM tabular list, quoted as published.

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

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Necrotizing enterocolitis in newborn, NOS

Coder workflow for P77.9

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

Before you code P77.9

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, P77.9 may be the appropriate code. Check the record for detail that supports a more specific sibling — in this subcategory the siblings differ by stage. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewP77.1, P77.2, P77.3

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — P77.9 is appropriate when the documentation goes no further.

    ReviewP77.1, P77.2, P77.3

Consider P77.9. 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.
Any detail beyond this code’s title
What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Coding decision scenarios

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

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewP77.1, P77.2, P77.3

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.

Code Overview

Necrotizing enterocolitis in newborn, unspecified is a billable ICD-10-CM diagnosis code (P77.9).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (1)

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.

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

Other codes that name P77.9 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: K55 — Vascular disorders of intestine (via P77.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 1 Excludes2 note: P37 — Other congenital infectious and parasitic diseases (via P77.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

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 36 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: 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):PNL012 — Neonatal digestive and feeding 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.

P29.89 — Other cardiovascular disorders originating in the perinatal period, P29.9 — Cardiovascular disorder originating in the perinatal period, unspecified, P76.0 — Meconium plug syndrome, P76.1 — Transitory ileus of newborn, P76.2 — Intestinal obstruction due to inspissated milk, P76.8 — Other specified intestinal obstruction of newborn, P76.9 — Intestinal obstruction of newborn, unspecified, P77.1 — Stage 1 necrotizing enterocolitis in newborn, P77.2 — Stage 2 necrotizing enterocolitis in newborn, P77.3 — Stage 3 necrotizing enterocolitis in newborn, P78.0 — Perinatal intestinal perforation, P78.1 — Other neonatal peritonitis, P78.2 — Neonatal hematemesis and melena due to swallowed maternal blood, P78.3 — Noninfective neonatal diarrhea, P78.81 — Congenital cirrhosis (of liver), P78.82 — Peptic ulcer of newborn, P78.83 — Newborn esophageal reflux, P78.84 — Gestational alloimmune liver disease, P78.89 — Other specified perinatal digestive system disorders, P78.9 — Perinatal digestive system disorder, unspecified, +15 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Intestinal Obstruction/Perforation) for risk-adjusted payment.

K65.3 — Choleperitonitis, K65.4 — Sclerosing mesenteritis, K65.8 — Other peritonitis, K65.9 — Peritonitis, unspecified, K67 — Disorders of peritoneum in infectious diseases classified elsewhere, K68.12 — Psoas muscle abscess, K68.19 — Other retroperitoneal abscess, P77.1 — Stage 1 necrotizing enterocolitis in newborn, P77.2 — Stage 2 necrotizing enterocolitis in newborn, P77.3 — Stage 3 necrotizing enterocolitis in newborn, P78.0 — Perinatal intestinal perforation, Q40.0 — Congenital hypertrophic pyloric stenosis, Q41.0 — Congenital absence, atresia and stenosis of duodenum, Q41.1 — Congenital absence, atresia and stenosis of jejunum, Q41.2 — Congenital absence, atresia and stenosis of ileum, Q41.8 — Congenital absence, atresia and stenosis of other specified parts of small intestine, Q41.9 — Congenital absence, atresia and stenosis of small intestine, part unspecified, Q42.0 — Congenital absence, atresia and stenosis of rectum with fistula, Q42.1 — Congenital absence, atresia and stenosis of rectum without fistula, Q42.2 — Congenital absence, atresia and stenosis of anus with fistula, +55 more

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Intestine Transplant Status/Complications

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Neonatal digestive and feeding disorders).

P76.0 — Meconium plug syndrome, P76.1 — Transitory ileus of newborn, P76.2 — Intestinal obstruction due to inspissated milk, P76.8 — Other specified intestinal obstruction of newborn, P76.9 — Intestinal obstruction of newborn, unspecified, P77.1 — Stage 1 necrotizing enterocolitis in newborn, P77.2 — Stage 2 necrotizing enterocolitis in newborn, P77.3 — Stage 3 necrotizing enterocolitis in newborn, P78.0 — Perinatal intestinal perforation, P78.1 — Other neonatal peritonitis, P78.2 — Neonatal hematemesis and melena due to swallowed maternal blood, P78.3 — Noninfective neonatal diarrhea, P78.81 — Congenital cirrhosis (of liver), P78.82 — Peptic ulcer of newborn, P78.83 — Newborn esophageal reflux, P78.84 — Gestational alloimmune liver disease, P78.89 — Other specified perinatal digestive system disorders, P78.9 — Perinatal digestive system disorder, unspecified, P92.01 — Bilious vomiting of newborn, P92.09 — Other vomiting of newborn, +8 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, K55.059 — Acute (reversible) ischemia of intestine, part and extent unspecified (hemorrhagic), K55.1 — Chronic vascular disorders of intestine (hemorrhagic, chronic), K55.30 — Necrotizing enterocolitis, unspecified (necrotizing), K55.31 — Stage 1 necrotizing enterocolitis (necrotizing, in non-newborn, stage 1), K55.32 — Stage 2 necrotizing enterocolitis (necrotizing, with, pneumatosis), K55.33 — Stage 3 necrotizing enterocolitis (necrotizing, with, perforation), K55.9 — Vascular disorder of intestine, unspecified (ischemic)

Contextual Map

Every relationship of P77.9 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.

Run P77.9 with these 2 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 78 — Intestinal Obstruction/Perforation [CMS-HCC]— CMS-HCC V28 · 2026

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 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

Index entries

  • Enterocolitis, necrotizing, in newborn[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

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
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
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release 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

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "P77.9 — Necrotizing enterocolitis in newborn, unspecified." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/p77.9-necrotizing-enterocolitis-in-newborn-unspecified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Necrotizing enterocolitis in newborn, unspecified

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to P77.9 in its code family, with their registry titles.

View all codes in the P77 family