ICD-10 Code I32: Pericarditis in diseases classified elsewhere

Key Takeaways

ICD-10 Code I32 is a billable diagnosis code for pericarditis in diseases classified elsewhere, valid for FY2026 from October 1, 2025 through September 30, 2026.

I32 is a manifestation code: the underlying disease driving it, such as histoplasmosis or chronic kidney disease (uremic pericarditis), must be sequenced first, but excluded etiologies like tuberculosis and lupus have their own combination code and must never be paired with I32.

Common coding errors include using I32 as a standalone primary code or omitting the required etiology code, which triggers claim denial.

Pabau’s claims management software helps cardiology and primary care practices apply etiology-first sequencing rules and reduce ICD-10 coding errors at the point of documentation.

ICD-10 Code I32 is the diagnosis code for pericarditis in diseases classified elsewhere, meaning pericardial inflammation that shows up as a manifestation of another underlying disease. It is billable for FY2026, but it is never reported on its own: the underlying disease is sequenced first, then I32 as the secondary code.

This guide covers what I32 means, how to tell it apart from the other pericarditis ICD-10 codes, the seven etiologies excluded from it, the present on admission rules, and the documentation that keeps these claims from being denied.

ICD-10 Code I32: Definition, billability, and FY2026 status

ICD-10 Code I32 is a billable ICD-10-CM diagnosis code that represents pericarditis in diseases classified elsewhere. It sits within the I30-I5A block (Other forms of heart disease) under Chapter IX of the ICD-10-CM tabular list, which covers diseases of the circulatory system (I00-I99). The 2026 edition became effective on October 1, 2025, and remains valid through September 30, 2026.

What makes I32 distinct from other pericarditis codes is its role as a secondary code. It cannot stand alone on a claim.

The pericarditis it describes is a manifestation of an underlying disease coded elsewhere in ICD-10-CM, which means the underlying condition must always be listed first. Misunderstanding this sequencing requirement is the most common source of claim denials for this code.

According to the CDC/NCHS ICD-10-CM web tool, I32 is classified as a billable, specific diagnosis code suitable for reimbursement purposes. Coders and clinicians searching for the right pericarditis code need to confirm whether the condition arises independently or as a consequence of another disease before selecting I32 versus codes like I30 or I31.

I32 code information at a glance

The table below provides a quick-reference summary of ICD-10 Code I32’s core attributes for FY2026.

Code hierarchy: Where ICD-10 Code I32 sits in ICD-10-CM

Understanding where I32 sits within the broader ICD-10-CM structure matters for two reasons. First, it helps coders navigate to the right code quickly. Second, it clarifies which parent-level excludes notes and coding conventions apply.

The I30-I5A block covers a wide range of cardiac conditions beyond coronary artery disease, including pericarditis (I30-I32), endocarditis and heart valve disorders (I33-I39), and cardiomyopathy (I42-I43). Coders working with cardiac diagnoses should be familiar with the sibling codes in this block to avoid selecting the wrong pericarditis code.

For reference, similar diagnostic coding patterns appear in other specialty areas, such as M35.3, where understanding code hierarchy prevents missequencing errors.

Manifestation code rule: Code the underlying disease first

I32 is a manifestation code. Under ICD-10-CM Official Guidelines Section I.A.13, manifestation codes describe conditions that are the result of an underlying disease and may not be used as the principal diagnosis. The underlying etiology must be coded and sequenced first.

This is not optional. Submitting I32 as a standalone primary code will result in a claim rejection from most payers. The correct sequencing is always: etiology code first, then I32 as the secondary manifestation code.

• Step 1: Identify the underlying disease causing the pericarditis, and confirm it is not one of the etiologies excluded from I32 (tuberculosis, systemic lupus erythematosus, rheumatoid arthritis, syphilis, coxsackievirus, gonococcal, or meningococcal infection each have their own combination code and are never paired with I32).
• Step 2: Locate and verify the ICD-10-CM code for that underlying condition.
• Step 3: Sequence the underlying disease code first on the claim.
• Step 4: Add ICD-10 Code I32 as the secondary manifestation code.
• Step 5: Confirm documentation supports both the underlying diagnosis and the pericarditis manifestation.

Before working through these steps, confirm the underlying disease is not one of the seven etiologies on I32’s Excludes1 list (see the Excludes notes section below). For those conditions — including tuberculous and lupus pericarditis — the combination code is reported alone, and I32 is not added.

This etiology-first rule applies regardless of the clinical setting. Whether the encounter is inpatient or outpatient, the underlying disease drives the sequencing.

The same discipline carries over to other ICD-10-CM entries, including O74.2, where documentation must capture both the underlying procedure and its complication accurately. N08 follows the same pattern for glomerular disorders, sequencing the systemic disease before the renal manifestation.

Common underlying conditions coded with ICD-10 Code I32

Only a small number of underlying diseases are actually reported alongside I32. The table below lists the two etiologies with documented ICD-10-CM support for pairing with I32: histoplasmosis, confirmed by a “use additional code” note under the relevant B39 subcategory in the tabular list, and uremic pericarditis, confirmed under “Pericarditis, uremic” in the alphabetic index.

The tabular “Code first” note under I32 itself is generic (“Code first: underlying disease”) and does not name specific etiologies. Other causes of secondary pericarditis — including tuberculosis and lupus — are excluded from I32 entirely and are covered in the Excludes notes section below.

Clinical documentation must clearly establish the causal relationship between the underlying disease and the pericardial inflammation. A chart that simply notes “pericarditis” without documenting the associated systemic disease will not support I32 billing. This is a frequent audit finding in cardiology, infectious disease, and functional medicine practices, where several systemic diagnoses often coexist in the same chart.

Before assigning I32, also confirm the underlying disease is not one of the seven Excludes1 etiologies covered below. Those are billed with a single combination code, without I32.

Approximate synonyms and index terms for I32

The ICD-10-CM alphabetical index and tabular list map several clinical terms to I32. Coders often encounter these synonyms in physician documentation and need to recognize that they all route to the same code.

• Histoplasmosis pericarditis
• Histoplasmosis with pericarditis
• Pericarditis, uremic (indexed to code first the underlying chronic kidney disease, then I32)
• Pericarditis in diseases classified elsewhere (primary index term)
• Secondary pericarditis (when caused by a classifiable underlying disease that is not excluded from I32, such as histoplasmosis or uremic pericarditis)

When physician documentation uses the histoplasmosis or uremic phrasing above, I32 is the appropriate manifestation code to assign, provided the underlying etiology is also coded and sequenced first. Coders unfamiliar with this index entry sometimes default to I30 (Acute pericarditis) incorrectly, which would represent primary rather than secondary pericarditis.

Excludes notes for ICD-10 Code I32

I32 carries excludes notes that define the boundaries of its use. Understanding whether a note is Excludes1 or Excludes2 determines whether the excluded codes can appear on the same claim.

These seven Excludes1 notes share a common logic. Each names an etiology-specific pericarditis that already has its own complete combination code, so adding I32 on top of it would double-code the same manifestation.

This is different from I32’s relationship with codes like I30 (Acute pericarditis) or I31 (Other diseases of pericardium). Those codes are not on I32’s Excludes1 list, but they are still distinguished from I32 by whether a classifiable underlying disease is documented.

A coder who adds I32 alongside any of the seven excluded codes above will create a diagnosis-code conflict that most payers’ claim-editing systems will flag or deny. Verify the excludes structure for I32 using the AAPC ICD-10-CM lookup or the official CDC tabular list.

Related pericarditis ICD-10 codes and how to tell them apart

Choosing the correct pericarditis ICD-10 code comes down to what the documentation supports: whether the pericarditis stands alone, involves an effusion or tamponade, has turned constrictive, or is a manifestation of another disease.

The table below maps each scenario to the right code in the I30-I5A block, so you can confirm whether I32 applies before the claim goes out. Acute pericarditis ICD-10 assignments (I30 and its subtypes) are primary codes, while I32 is always secondary.

The most clinically nuanced distinction is between I30.1 (Infective pericarditis) and I32. When a bacterial or viral infection causes pericarditis and is documented as the primary reason for the encounter, I30.1 may be the appropriate code.

I32 applies when the pericarditis is specifically noted as a manifestation of a classifiable underlying disease that is not excluded from I32, such as histoplasmosis coded at the appropriate B39 subcategory, or chronic kidney disease (uremic pericarditis), coded first with N18.9. The CMS ICD-10 codes page provides the current FY2026 tabular list and guidelines for resolving these distinctions.

A documented viral pericarditis ICD-10 case maps to I30, typically I30.0 or I30.1, not I32, unless a classifiable systemic disease drives it. Recurrent pericarditis ICD-10 coding follows the same logic: the recurrence is captured under I30 unless the record ties it to a codable underlying disease.

Present on admission (POA) indicator for I32

For inpatient claims submitted to Medicare and Medicaid, the Present on Admission (POA) indicator must accompany every diagnosis code, including I32. The POA indicator tells the payer whether the condition was present at the time of admission or developed during the hospital stay.

• Y (Yes): The pericarditis was present when the patient was admitted.
• N (No): The pericarditis developed after the patient was admitted (hospital-acquired).
• U (Unknown): Documentation does not allow a determination of POA status.
• W (Clinically undetermined): Provider cannot determine if the condition was POA.

I32 is not on the CMS POA exempt list, so POA reporting is required for inpatient claims. Since I32 is always a secondary manifestation code, the POA indicator applies to both I32 and the sequenced etiology code. Both must carry the appropriate POA indicator.

Coders should check the current CMS POA exempt list at the start of each fiscal year to confirm whether any changes affect their workflows. The primary care compliance checklist offers related guidance on documentation requirements for claim accuracy.

Pericarditis coding guidelines and documentation tips

Accurate coding for I32 depends on the quality of the clinical note. Coders cannot infer the causative relationship between pericarditis and an underlying disease; the physician must document it explicitly.

A structured note format, like an APSO note template, gives clinicians a consistent place to record that causal link during the encounter itself. These documentation requirements apply whether the encounter is inpatient or outpatient.

• Document the causal link explicitly: Phrases such as “pericarditis due to,” “pericarditis secondary to,” or “pericarditis caused by” are needed to support I32 assignment. “Pericarditis and histoplasmosis” is not sufficient.
• Confirm the underlying diagnosis: The disease must itself be coded using a specific ICD-10-CM code, and must not be one of the seven etiologies excluded from I32. Coding I32 with an unspecified or residual etiology code can trigger additional scrutiny.
• Do not use I32 as principal diagnosis: If I32 appears in the principal diagnosis slot on an inpatient record, it should be flagged for query. The underlying disease drives the MS-DRG grouping.
• Review excludes notes before finalizing: Confirm the underlying disease is not one of I32’s seven Excludes1 etiologies (coxsackievirus, gonococcal, meningococcal, rheumatoid arthritis, syphilis, systemic lupus erythematosus, or tuberculosis) or rheumatic pericarditis (I09.2); each of those is coded alone instead of with I32.
• Apply POA indicators to both codes: Both the etiology code and I32 require POA indicators on inpatient claims.

Effective clinical documentation workflows help catch these issues before claim submission rather than after denial. Practices using structured medical forms, such as a client information template, can build prompts into their intake and encounter templates to ensure the causal relationship is captured at the point of care.

Similarly, clinical documentation tools that surface relevant code guidance during charting reduce the missing documentation that causes I32 claims to be returned.

How Pabau supports accurate ICD-10 coding for pericarditis

Coding errors on manifestation codes like I32 rarely stem from a lack of coder knowledge. They stem from documentation workflows that do not prompt clinicians to capture the causal relationship at the right moment.

By the time a coder reviews the chart, the note may say “pericarditis” and “histoplasmosis” without the linking language required to support I32 billing. A coder may also miss that documented tuberculous or lupus pericarditis should be coded with A18.84 or M32.12 alone, without I32.

Pabau’s claims management software helps cardiology and internal medicine practices reduce this type of error by structuring the documentation and billing workflow around the clinical encounter. Clinicians can use digital intake forms configured to capture presenting conditions and their relationships, which surfaces the data coders need without requiring a physician addendum.

The platform’s EHR integration connects the clinical note directly to billing, reducing the lag time between documentation and claim submission where errors tend to accumulate.

For practices managing HIPAA-compliant practice management across multiple providers, Pabau’s centralized record structure ensures that the etiology and manifestation codes are visible together in the patient record, making sequencing errors easier to catch during internal review.

Practices that want to see how this works in their specific cardiology, internal medicine, or general practice workflow can book a demo to walk through the billing module.

Conclusion

ICD-10 Code I32 is a precise but often misused code. Three requirements create the most common failure points for denial or audit exposure:

• Sequencing the correct underlying disease first
• The Excludes1 restriction that bars I32 from seven etiology-specific pericarditis codes, including tuberculous and lupus pericarditis, each billed alone
• The POA indicator obligation on inpatient claims

Getting them right depends less on memorizing the rules and more on having documentation workflows that capture the clinical information at the point of care.

Pabau’s practice management software helps clinical teams build those workflows into the encounter itself, so coders receive notes that already contain the causal language and etiology detail needed to assign I32 correctly.

Reduce ICD-10 coding errors with Pabau

Pabau helps cardiology and internal medicine practices structure clinical documentation so that manifestation codes like I32 are sequenced correctly from the first submission. See how the billing and EHR workflow works for your practice.

Book a demo

Continue your research

Want to strengthen the clinical notes that support your coding? Nursing documentation covers the standards that keep causal relationships clear and audit-ready.

Billing for a different specialty? The chiropractic billing cheat sheet walks through sequencing and documentation rules for another commonly miscoded specialty.

Need guidance on a related symptom code? R81 explains billability and sequencing for another commonly confused ICD-10-CM entry.

Frequently asked questions