2026 ICD-10-CM Diagnosis Code I31.8Other specified diseases of pericardium

ICD-10-CM Codes›I00–I99›I30-I5A›I31

ICD-10-CM I31.8
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I31.8 is a billable ICD-10-CM diagnosis code for other specified diseases of pericardium. 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
I31.8
Billable Status
Yes — Valid for Submission
Code Describes
Other specified diseases of pericardium
Short Description
Other specified diseases of pericardium
Same as the full description in the CMS dataset.
Parent Code
I31
Other diseases of pericardium

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI31Other diseases of pericardium
This CodeI31.8Other specified diseases of pericardium

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Abnormal communication between pericardial sac and pleura
  • Abnormal pericardiopleural communication
  • Acquired pericardial cyst
  • Cyst of mediastinum
  • Deposition of excess fat on visceral pericardium
  • Fistula of pericardium
  • Malignant neoplasm of pericardium
  • Metastatic malignant neoplasm to pericardium
  • Milk spots of pericardium
  • Pericardial cyst
  • Pericardial cyst along left cardiophrenic angle
  • Pericardial defect
  • Pericarditis caused by deposits of cholesterol
  • Pericarditis due to metastatic malignant neoplasm to pericardium
  • Pericarditis secondary to benign primary tumor
  • Pericarditis secondary to malignant primary tumor
  • Pericarditis secondary to neoplasia
  • Pericarditis secondary to primary tumor
  • Post-cardiac injury syndrome

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Epicardial plaques
  • Focal pericardial adhesions

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.

    • Adhesions, adhesive(postinfective)
      • pericardium (nonrheumatic)
        • focal
    • Cyst(colloid) (mucous) (simple) (retention)
      • pericardial (congenital)
        • acquired (secondary)
    • Diverticulum, diverticula(multiple)
      • pericardium (congenital) (cyst)
        • acquired
    • Fistula(cutaneous)
      • pleuropericardial
    • Mediastinopericarditis
      • chronic
    • Pericarditis(with decompensation) (with effusion)
      • cholesterol (chronic)
    • Pericarditis(with decompensation) (with effusion)
      • neoplastic (chronic)
    • Plaque(s)
      • epicardial

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

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 I31.8 to ICD-9-CMHistory

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

ICD-9-CM
423.8 Pericardial disease 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 I31.8Overview

Is I31.8 (Other diseases of pericardium) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other specified diseases of pericardium on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I31.8 group to?

When other specified diseases of pericardium 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 I31.8?

Under the General Equivalence Mappings, other specified diseases of pericardium converts to ICD-9-CM 423.8 (pericardial disease 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.