2026 ICD-10-CM Diagnosis Code I31.8Other specified diseases of pericardium
ICD-10-CM Codes›I00–I99›I30-I5A›I31
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
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. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 17 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Pericarditis and pericardial disease.
Code Identity
Code Classification
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
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Mediastinopericarditis See Also: Pericarditis;
chronic I31.8
Pericarditis (with decompensation) (with effusion) I31.9
cholesterol (chronic) I31.8
neoplastic (chronic) I31.8
epicardial I31.8
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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.
Code HistoryHistory
Questions About I31.8Overview
What is the ICD-10 code for other specified diseases of pericardium?
The ICD-10-CM code for other specified diseases of pericardium is I31.8 (sometimes written as I318). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
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.
Is I31.8 a CC or MCC?
CMS lists I31.8 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 17 closely related codes in its exclusion list.
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.
