P91.63 ICD-10-CM Code: Severe hypoxic ischemic encephalopathy [HIE]

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for P91.63 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 P91.63 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for P91.63

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

Before you code P91.63

1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with P91.63. 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 P91.63’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.

   ReviewP91.4, P91.3, P91.5

Consider P91.63. 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).

Severity

Mild, moderate or severe as the provider states it; severity is not inferred from the clinical picture.

Official instructions as workflow

• Excludes1 — check before selecting P91.63(3 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with P91.63: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareP91.4, P91.3, P91.5

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

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.

• Encephalopathy (acute), hypoxic ischemic, severe
• Newborn (infant) (liveborn) (singleton), affected by, hypoxic ischemic encephalopathy [HIE], severe

Don’t confuse P91.63 with…

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

The codes most likely to be picked instead of P91.63 — 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.

• P91.4— 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 Neonatal cerebral depression moves the case to P91.4; the two are not reported together unless documented as unrelated.

  Full comparison: P91.63 vs P91.4 →

• P91.3— 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 Neonatal cerebral irritability moves the case to P91.3; the two are not reported together unless documented as unrelated.

  Full comparison: P91.63 vs P91.3 →

• P91.5— 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 Neonatal coma moves the case to P91.5; the two are not reported together unless documented as unrelated.

  Full comparison: P91.63 vs P91.5 →

• P91.60— 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 “Hypoxic ischemic encephalopathy [HIE], unspecified” takes P91.60; specificity in the record moves it back here.

  Full comparison: P91.63 vs P91.60 →

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

Other codes that name P91.63 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: P84 — Other problems with newborn (via P91.6.-).

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

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 5 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):PNL004 — Neonatal cerebral 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.

P84 — Other problems with newborn, P91.60 — Hypoxic ischemic encephalopathy [HIE], unspecified, P91.61 — Mild hypoxic ischemic encephalopathy [HIE], P91.62 — Moderate hypoxic ischemic encephalopathy [HIE]

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Coma, Brain Compression/Anoxic Damage) for risk-adjusted payment.

G93.6 — Cerebral edema, P91.0 — Neonatal cerebral ischemia, P91.1 — Acquired periventricular cysts of newborn, P91.2 — Neonatal cerebral leukomalacia, P91.3 — Neonatal cerebral irritability, P91.4 — Neonatal cerebral depression, P91.5 — Neonatal coma, P91.60 — Hypoxic ischemic encephalopathy [HIE], unspecified, P91.61 — Mild hypoxic ischemic encephalopathy [HIE], P91.62 — Moderate hypoxic ischemic encephalopathy [HIE], P91.811 — Neonatal encephalopathy in diseases classified elsewhere, P91.819 — Neonatal encephalopathy, unspecified, P91.88 — Other specified disturbances of cerebral status of newborn, P91.9 — Disturbance of cerebral status of newborn, unspecified, R40.20 — Unspecified coma, R40.2110 — Coma scale, eyes open, never, unspecified time, R40.2111 — Coma scale, eyes open, never, in the field [EMT or ambulance], R40.2112 — Coma scale, eyes open, never, at arrival to emergency department, R40.2113 — Coma scale, eyes open, never, at hospital admission, R40.2114 — Coma scale, eyes open, never, 24 hours or more after hospital admission, +40 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.

Major Head Injury with Loss of Consciousness > 1 Hour, Major Head Injury with Loss of Consciousness < 1 Hour or Unspecified, Chronic Liver Failure/End-Stage Liver Disorders

Same clinical category (CCSR)

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

P90 — Convulsions of newborn, P91.0 — Neonatal cerebral ischemia, P91.1 — Acquired periventricular cysts of newborn, P91.2 — Neonatal cerebral leukomalacia, P91.3 — Neonatal cerebral irritability, P91.4 — Neonatal cerebral depression, P91.5 — Neonatal coma, P91.60 — Hypoxic ischemic encephalopathy [HIE], unspecified, P91.61 — Mild hypoxic ischemic encephalopathy [HIE], P91.62 — Moderate hypoxic ischemic encephalopathy [HIE], P91.8 — Other specified disturbances of cerebral status of newborn, P91.811 — Neonatal encephalopathy in diseases classified elsewhere, P91.819 — Neonatal encephalopathy, unspecified, P91.821 — Neonatal cerebral infarction, right side of brain, P91.822 — Neonatal cerebral infarction, left side of brain, P91.823 — Neonatal cerebral infarction, bilateral, P91.829 — Neonatal cerebral infarction, unspecified side, P91.88 — Other specified disturbances of cerebral status of newborn, P91.9 — Disturbance of cerebral status of newborn, unspecified

Same Index main term, other category

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

P74.1 — Dehydration of newborn (dehydration), P74.21 — Hypernatremia of newborn (hypernatremia), P74.22 — Hyponatremia of newborn (hyponatremia), P74.8 — Other transitory metabolic disturbances of newborn (affected by, amino-acid metabolic disorder, transitory), P78.0 — Perinatal intestinal perforation (affected by, meconium peritonitis), P81.0 — Environmental hyperthermia of newborn (fever, environmentally-induced), P81.9 — Disturbance of temperature regulation of newborn, unspecified (fever), P83.4 — Breast engorgement of newborn (breast engorgement), P84 — Other problems with newborn (affected by, mixed metabolic and respiratory acidosis), P90 — Convulsions of newborn (seizure), P92.01 — Bilious vomiting of newborn (vomiting, bilious), P92.09 — Other vomiting of newborn (vomiting), P96.1 — Neonatal withdrawal symptoms from maternal use of drugs of addiction (abstinence syndrome), P96.5 — Complication to newborn due to (fetal) intrauterine procedure (affected by, intrauterineprocedure), P96.89 — Other specified conditions originating in the perinatal period (breast buds), Q07.9 — Congenital malformation of nervous system, unspecified (congenital), QA0.0151 — FOXG1 syndrome (FOXG1-related), R68.13 — Apparent life threatening event in infant (ALTE) (affected by, apparent life threatening event), T80.69 — Other serum reaction due to other serum (in, serum), Z00.110 — Health examination for newborn under 8 days old (examination, under 8 days old), +180 more

Contextual Map

Every relationship of P91.63 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 P91.63 with this related code in Claim Check

Hierarchy

• P00-P96 — Chapter 16: Certain Conditions Originating in the Perinatal Period (P00-P96) (P00-P96)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Excludes1 notes

• P84 — Other problems with newborn[Excludes1](via P91.6.-): “hypoxic ischemic encephalopathy [HIE] (P91.6-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• PNL004 — Neonatal cerebral disorders[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

Risk adjustment (CMS-HCC)

• HCC 202 — Coma, Brain Compression/Anoxic Damage [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

• 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

• Encephalopathy (acute), hypoxic ischemic, severe[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Newborn (infant) (liveborn) (singleton), affected by, hypoxic ischemic encephalopathy [HIE], severe[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (22)

• P91 — Other disturbances of cerebral status of newborn[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P91.0 — Neonatal cerebral ischemia[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P91.1 — Acquired periventricular cysts of newborn[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P91.2 — Neonatal cerebral leukomalacia[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P91.3 — Neonatal cerebral irritability[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P91.4 — Neonatal cerebral depression[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P91.5 — Neonatal coma[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P91.6 — Hypoxic ischemic encephalopathy [HIE][Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 14 more

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

Nearest Codes in This Family

Official ICD-10-CM classifications closest to P91.63 in its code family, with their registry titles.

• P91.5 — Neonatal coma
• P91.6 — Hypoxic ischemic encephalopathy [HIE]
• P91.60 — Hypoxic ischemic encephalopathy [HIE], unspecified
• P91.61 — Mild hypoxic ischemic encephalopathy [HIE]
• P91.62 — Moderate hypoxic ischemic encephalopathy [HIE]
• P91.8 — Other specified disturbances of cerebral status of newborn
• P91.81 — Neonatal encephalopathy
• P91.811 — Neonatal encephalopathy in diseases classified elsewhere
• P91.819 — Neonatal encephalopathy, unspecified
• P91.82 — Neonatal cerebral infarction

View all codes in the P91 family