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ICD-10-CM P91.821: Neonatal cerebral infarction, right side of brain

P91.821 is the billable ICD-10-CM code for neonatal cerebral infarction, right side of brain, in category P91 (Other disturbances of cerebral status of newborn) of the Other disorders originating in the perinatal period section. As a principal diagnosis it groups to MS-DRG 791 Prematurity with Major Problems, MS-DRG 793 Full Term Neonate with Major Problems (MDC 15 MDC 15: Newborns and Other Neonates with Conditions Originating in Perinatal Period). It maps to HCC 249 (Ischemic or Unspecified Stroke) in CMS-HCC V28. As a secondary diagnosis it is an MCC, excluded with 4 principal diagnoses. 1 LCD billing and coding article lists it as covered.

Compiled from CMS files by the QuickIntell RCM Editorial Team · Data effective · Method: reference methodology · Report a data correction

Data currency: ICD-10-CM code descriptions: FY2027 (effective October 1, 2026); IPPS Table 5 (MS-DRG weights): v44 FY2027 (final rule + CN3) (effective October 1, 2026); ICD-10-CM to HCC mapping: PY2027 initial ICD-10-CM mappings (dates of service 2026) (payment year 2027); Medicare Coverage Database billing and coding articles: MCD release October 8, 2026 (effective October 4, 2026). Next CMS release: FY2028 code files, effective October 1, 2027 for the ICD-10-CM code descriptions; FY2028 final rule (August 2027), effective October 1, 2027; an April 1 interim grouper update when CMS issues one for the IPPS Table 5 (MS-DRG weights); PY2028 advance notice (February 2027) and the PY2027 midyear final mapping (spring 2027) for the ICD-10-CM to HCC mapping; weekly, every Thursday for the Medicare Coverage Database billing and coding articles.

Code
P91.821
billable FY2027 ICD-10-CM code
Category
P91 Other disturbances of cerebral status of newborn
Chapter
16: Certain conditions originating in the perinatal period (P00-P96)
CC/MCC (MS-DRG v44)
MCC
CMS-HCC V28
HCC 249
POA reporting
Exempt

Tabular list notes for P91.821

The tabular list has no notes on P91.821 itself; the notes below apply from its parent headings.

Inherited from P91.82 (Neonatal cerebral infarction)

Inclusion terms
  • Neonatal stroke
  • Perinatal arterial ischemic stroke
  • Perinatal cerebral infarction
Excludes1 (never coded together)
  • cerebral infarction (I63.-)
Excludes2 (not part of this condition, may be coded together)
  • intracranial hemorrhage of newborn (P52.-)

MS-DRG grouping when P91.821 is the principal diagnosis

MS-DRG v44 groups for P91.821 as principal diagnosis
MDCMS-DRGs
15 MDC 15: Newborns and Other Neonates with Conditions Originating in Perinatal Period791793

The final group also depends on procedures, secondary diagnoses and discharge status; the MS-DRG lookup for P91.821 shows the full grouping logic.

CC/MCC status and inpatient edits

As a secondary diagnosis, P91.821 is an MCC under MS-DRG v44, unless the principal diagnosis is one of the 4 codes in its exclusion list. Check P91.821 against a principal diagnosis.

  • Present on admission: exempt from POA indicator reporting (FY2027 exempt list).

CMS-HCC V28 risk adjustment

In the PY2027 mapping, P91.821 maps to HCC 249 (Ischemic or Unspecified Stroke). The HCC lookup shows the RAF weight and the hierarchy.

LCD billing and coding articles that list P91.821

1 current Medicare billing and coding article lists P91.821 among the diagnoses that support medical necessity for the services they cover.

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Frequently asked questions

What does ICD-10-CM P91.821 mean?

P91.821 means neonatal cerebral infarction, right side of brain. It is one of 18 billable codes under P91, other disturbances of cerebral status of newborn.

What can't be coded with P91.821?

Excludes1 at P91.82: cerebral infarction (I63.-). These are never reported together with P91.821.

Which MS-DRG does P91.821 group to?

As the principal diagnosis, P91.821 groups to MS-DRG 791 Prematurity with Major Problems, MS-DRG 793 Full Term Neonate with Major Problems (MDC 15 MDC 15: Newborns and Other Neonates with Conditions Originating in Perinatal Period) under MS-DRG v44, before procedures and secondary diagnoses are applied.

Does P91.821 map to an HCC?

Yes: HCC 249, Ischemic or Unspecified Stroke, in the PY2027 CMS-HCC V28 mapping.

Is P91.821 a CC or MCC?

P91.821 is an MCC under MS-DRG v44; 4 principal diagnoses exclude it.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Disclaimer

The descriptor and notes are reproduced from the FY2027 ICD-10-CM files; MS-DRG, CC/MCC and HCC facts come from the CMS FY2027 and PY2027 tables. Code from the medical record and the ICD-10-CM Official Guidelines. Not legal, clinical or billing advice.

Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.