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ICD-10 Guide
ICD-10 CodesI33.9

I33.9

Billable

Acute and subacute endocarditis, unspecified

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/06/2025

Code Description

ICD-10 I33.9 is a billable code used to indicate a diagnosis of acute and subacute endocarditis, unspecified.

Key Diagnostic Point:

Acute and subacute endocarditis, unspecified, refers to an infection of the inner lining of the heart chambers and valves, which can lead to severe complications if not diagnosed and treated promptly. Clinically, patients may present with fever, chills, fatigue, and heart murmurs. The anatomy involved includes the heart valves, particularly the mitral and aortic valves, which are most commonly affected. Disease progression can be rapid in acute cases, leading to valvular insufficiency, embolic events, and heart failure. In subacute cases, symptoms may develop more gradually, often in patients with pre-existing heart conditions. Diagnostic considerations include blood cultures, echocardiography, and clinical criteria such as the Duke criteria, which help differentiate endocarditis from other cardiovascular conditions. Accurate diagnosis is crucial for effective treatment, which typically involves prolonged antibiotic therapy and, in some cases, surgical intervention.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Diagnostic complexity: Requires thorough clinical evaluation and laboratory testing.
  • Treatment complexity: Involves long-term antibiotic therapy and potential surgical intervention.
  • Documentation requirements: Must include detailed clinical findings and diagnostic tests.
  • Coding specificity: Limited specificity as it does not differentiate between types of endocarditis.

Audit Risk Factors

  • Common coding errors: Misclassification with other types of endocarditis.
  • Documentation gaps: Incomplete clinical notes or missing diagnostic criteria.
  • Billing challenges: Potential denials due to lack of specificity or supporting documentation.

Specialty Focus

Medical Specialties

Cardiology

Documentation Requirements

Standard ICD-10-CM documentation requirements apply

Common Clinical Scenarios

Various clinical presentations within this specialty area

Billing Considerations

Follow specialty-specific billing guidelines

Infectious Disease

Documentation Requirements

Standard ICD-10-CM documentation requirements apply

Common Clinical Scenarios

Various clinical presentations within this specialty area

Billing Considerations

Follow specialty-specific billing guidelines

Related ICD-10 Codes

Related CPT Codes

CPT Code

Clinical Scenario

Documentation Requirements

CPT Code

Clinical Scenario

Documentation Requirements

CPT Code

Clinical Scenario

Documentation Requirements

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The clinical significance of I33.9 lies in its potential to lead to serious complications such as heart failure, stroke, or systemic embolism if not treated promptly. Population health impact is notable, particularly in individuals with pre-existing heart conditions or those at risk for infections. Quality measures related to endocarditis management focus on timely diagnosis and appropriate treatment, which can improve healthcare utilization patterns. Epidemiologically, endocarditis remains a critical concern in cardiovascular health, with varying incidence rates based on population demographics and underlying health conditions.

ICD-9 vs ICD-10

The clinical significance of I33.9 lies in its potential to lead to serious complications such as heart failure, stroke, or systemic embolism if not treated promptly. Population health impact is notable, particularly in individuals with pre-existing heart conditions or those at risk for infections. Quality measures related to endocarditis management focus on timely diagnosis and appropriate treatment, which can improve healthcare utilization patterns. Epidemiologically, endocarditis remains a critical concern in cardiovascular health, with varying incidence rates based on population demographics and underlying health conditions.

Reimbursement & Billing Impact

Reimbursement considerations include ensuring that the medical necessity for diagnostic tests and treatments is clearly documented. Common denials may arise from insufficient documentation or lack of specificity in the diagnosis. Coders should ensure that all relevant clinical information is included in the medical record to support the use of I33.9 and related procedure codes. Best practices include regular training on coding updates and maintaining clear communication with healthcare providers to ensure accurate documentation.

Resources

Clinical References

  • •
    ICD-10 Official Guidelines for I00-I99
  • •
    Clinical Documentation Requirements

Coding & Billing References

  • •
    ICD-10 Official Guidelines for I00-I99
  • •
    Clinical Documentation Requirements

Frequently Asked Questions

What specific conditions are covered by I33.9?

I33.9 encompasses unspecified cases of acute and subacute endocarditis, which may include infections caused by bacteria, fungi, or other pathogens affecting the heart valves and lining.

When should I33.9 be used instead of related codes?

I33.9 should be used when the specific type of endocarditis cannot be determined or when the clinical documentation does not support a more specific diagnosis.

What documentation supports I33.9?

Documentation should include clinical findings such as symptoms, diagnostic test results (e.g., blood cultures, echocardiograms), and any relevant patient history that supports the diagnosis of endocarditis.