2026 ICD-10-CM Diagnosis Code I30.9Acute pericarditis, unspecified

ICD-10-CM Codes›I00–I99›I30-I5A›I30

ICD-10-CM I30.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I30.9 is a billable ICD-10-CM diagnosis code for acute pericarditis, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 314 through 316. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Pericarditis and pericardial disease.

Code Identity

ICD-10-CM Code
I30.9
Billable Status
Yes — Valid for Submission
Code Describes
Acute pericarditis, unspecified
Short Description
Acute pericarditis, unspecified
Same as the full description in the CMS dataset.
Parent Code
I30
Acute pericarditis

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI30Acute pericarditis
This CodeI30.9Acute pericarditis, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute bloody pericarditis
  • Acute mediastinitis
  • Acute mediastinopericarditis
  • Acute myocarditis
  • Acute myopericarditis
  • Acute pericardial effusion
  • Acute pericarditis
  • Acute pleuropericarditis
  • Acute pneumopericarditis
  • Myopericarditis
  • Pericarditis sicca
  • Pneumopericardium

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.

    • Chylopericardium
      • acute
    • Mediastinopericarditis
      • acute
    • Pericarditis(with decompensation) (with effusion)
      • acute (hemorrhagic) (nonrheumatic) (Sicca)
    • Pericarditis(with decompensation) (with effusion)
      • cholesterol (chronic)
        • acute
    • Pericarditis(with decompensation) (with effusion)
      • neoplastic (chronic)
        • acute
    • Pleuropericarditis
      • acute
    • Pneumopericarditis
      • acute

Clinical ClassificationClinical

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

CCSR CIR006
Pericarditis and pericardial disease
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Pneumopericardium

    presence of air or gas in the space between the heart and the pericardium. the degree of respiratory distress depends on the amount of trapped air and circulation blocked in the systemic and pulmonary veins.

  • Pericardium

    a conical fibro-serous sac surrounding the heart and the roots of the great vessels (aorta; venae cavae; pulmonary artery). pericardium consists of two sacs: the outer fibrous pericardium and the inner serous pericardium. the latter consists of an outer parietal layer facing the fibrous pericardium, and an inner visceral layer (epicardium) resting next to the heart, and a pericardial cavity between these two layers.

  • Acute Pericarditis

    acute inflammation of the pericardium.

  • Acute Pericarditis Related to COVID-19|Acute pericarditis

    acute pericarditis in a patient with probable or confirmed acute covid-19.

  • Acute Myocarditis

    the sudden onset of inflammation of heart muscle with myocellular necrosis; this is generally secondary to an infectious cause, and patients often have a recent history of a flu-like illness.

  • Pneumopericardium

    the presence of air in the pericardial cavity. causes include chest injury in adults, and respiratory distress syndrome in infants.

Patient EducationClinical

Pericardial Disorders

The pericardium is a membrane, or sac, that surrounds your heart. It holds the heart in place and helps it work properly. Problems with the pericardium include:

Read the full article at MedlinePlus

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

Convert I30.9 to ICD-9-CMHistory

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

ICD-9-CM
420.90 Acute pericarditis NOS
Approximate The match is approximate rather than exact.
ICD-9-CM
420.99 Acute pericarditis NEC
Approximate The match is approximate rather than exact.

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 I30.9Overview

Is I30.9 (Acute pericarditis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report acute pericarditis, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I30.9 group to?

When acute pericarditis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 314, 315, 316, with relative weights from 0.6821 to 2.0852 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I30.9?

Under the General Equivalence Mappings, acute pericarditis, unspecified converts to ICD-9-CM 420.90 (acute pericarditis NOS) and 420.99 (acute pericarditis NEC). The mapping is approximate, so confirm the match fits the documentation.

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.