2026 ICD-10-CM Diagnosis Code P91.63Severe hypoxic ischemic encephalopathy [HIE]

ICD-10-CM Codes›P00–P96›P90-P96›P91

ICD-10-CM P91.63
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

P91.63 is a billable ICD-10-CM diagnosis code for severe hypoxic ischemic encephalopathy [HIE]. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). Coders also document this condition as hypoxic ischemic encephalopathy. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Neonatal cerebral disorders.

Code Identity

ICD-10-CM Code
P91.63
Billable Status
Yes — Valid for Submission
Code Describes
Severe hypoxic ischemic encephalopathy [HIE]
Short Description
Severe hypoxic ischemic encephalopathy [HIE]
Same as the full description in the CMS dataset.
Parent Code
P91.6
Hypoxic ischemic encephalopathy [HIE]

Code Classification

ChapterP00–P96Certain conditions originating in the perinatal period
SectionP90-P96Other disorders originating in the perinatal period
CategoryP91Other disturbances of cerebral status of newborn
This CodeP91.63Severe hypoxic ischemic encephalopathy [HIE]

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Hypoxic ischemic encephalopathy
  • Hypoxic ischemic encephalopathy of newborn
  • Neonatal encephalopathy
  • Severe hypoxic ischemic encephalopathy
  • Severe hypoxic ischemic encephalopathy of newborn

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.

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

Clinical ClassificationClinical

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

CCSR PNL004
Neonatal cerebral disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • GAIA Level 1 Neonatal Encephalopathy|Global Alignment of Immunization safety Assessment in pregnancy Level 1 Neonatal Encephalopathy|Level 1 Neonatal Encephalopathy

    gaia level 1 neonatal encephalopathy is defined by three criteria: first, a newborn infant (1-28 days of life) born at or beyond 35 weeks of gestation; second, an abnormal level of alertness or seizures; third, difficulty with initiating and maintaining respiration; fourth, depression of muscle tone.

  • GAIA Level 2 Neonatal Encephalopathy|Global Alignment of Immunization safety Assessment in pregnancy Level 2 Neonatal Encephalopathy|Level 2 Neonatal Encephalopathy

    gaia level 2 neonatal encephalopathy is defined by three criteria: first, a newborn infant (1 to 28 days of life) born at or beyond 35 weeks of gestation; second, an abnormal level of alertness or seizures; third, either difficulty with initiating and maintaining respiration or depression of muscle tone.

  • GAIA Level 3 Neonatal Encephalopathy|Global Alignment of Immunization safety Assessment in pregnancy Level 3 Neonatal Encephalopathy|Level 3 Neonatal Encephalopathy

    gaia level 3 neonatal encephalopathy is defined by three criteria: first, a newborn infant (1-28 days of life) born at or beyond 35 weeks of gestation; second, an abnormal level of alertness or seizures; third, none of the following: a) difficulty with initiating or maintaining respiration; b) depression of muscle tone.

  • GAIA Neonatal Encephalopathy Level of Diagnostic Certainty Terminology|Global Alignment of Immunization safety Assessment in pregnancy Neonatal Encephalopathy Level of Diagnostic Certainty

    a subset of terminology related to neonatal encephalopathy, developed by the global alignment of immunization safety assessment in pregnancy consortium to aid in monitoring and improving fetal and maternal outcomes.

  • GAIA Neonatal Encephalopathy Level of Diagnostic Certainty|Global Alignment of Immunization safety Assessment in pregnancy Neonatal Encephalopathy Level of Diagnostic Certainty|Neonatal Encephalopathy Level of Diagnostic Certainty

    a classification of maternal and fetal outcomes relating to neonatal encephalopathy, developed by the global alignment of immunization safety assessment in pregnancy, based on the extent to which the diagnosis has been confirmed.

  • Neonatal Encephalopathy

    abnormal functioning of the central nervous system in the newborn period that may be due to a variety of etiologies including hypoxia/ischemia, metabolic disturbance, or infection.

  • Severe Neonatal Encephalopathy Due to MECP2 Mutations

    an x-linked recessive condition caused by mutation(s) in the mecp2 gene, encoding methyl-cpg-binding protein 2. it is characterized by severe neonatal encephalopathy.

Patient EducationClinical

Brain Diseases

Your brain is the control center of your body. It controls your thoughts, memory, speech, and movement. It regulates the function of many organs. It's part of your nervous system, which also includes your spinal cord and peripheral nerves. The nervous system sends signals between your brain and the rest of the body.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert P91.63 to ICD-9-CMHistory

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

ICD-9-CM
768.73 Sev hypox-ischem enceph
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About P91.63Overview

Is P91.63 (Hypoxic ischemic encephalopathy [HIE]) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report severe hypoxic ischemic encephalopathy [HIE] on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What is the ICD-9 equivalent of P91.63?

Under the General Equivalence Mappings, severe hypoxic ischemic encephalopathy [HIE] converts to ICD-9-CM 768.73 (sev hypox-ischem enceph). The mapping is a direct match.

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.