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ICD-10 Guide
ICD-10 CodesA42.9

A42.9

Actinomycosis, unspecified

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/05/2025

Code Description

ICD-10 A42.9 is a billable code used to indicate a diagnosis of actinomycosis, unspecified.

Key Diagnostic Point:

Actinomycosis is a chronic bacterial infection caused by Actinomyces species, which are anaerobic, gram-positive bacteria. This condition primarily affects the cervicofacial region, thorax, and abdomen, but can also occur in other areas of the body. The infection is characterized by the formation of abscesses, draining sinuses, and the presence of sulfur granules in pus. Actinomycosis is often associated with immunocompromised states, such as those seen in patients with HIV/AIDS, diabetes, or those undergoing immunosuppressive therapy. The diagnosis can be challenging due to its nonspecific symptoms and the need for specific culture techniques to identify the organism. In immunocompromised patients, actinomycosis can present more aggressively and may mimic other opportunistic infections, complicating the diagnostic process. Clinicians must maintain a high index of suspicion, especially in patients with risk factors, as early diagnosis and treatment are crucial for favorable outcomes. Treatment typically involves prolonged antibiotic therapy, and in some cases, surgical intervention may be necessary to drain abscesses or remove infected tissue.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variability in clinical presentation and symptoms
  • Need for specific laboratory tests for diagnosis
  • Potential overlap with other opportunistic infections
  • Documentation of immunocompromised status

Audit Risk Factors

  • Inadequate documentation of immunocompromised status
  • Failure to specify the site of infection
  • Lack of supporting lab results
  • Misclassification of actinomycosis as another infection

Specialty Focus

Medical Specialties

Infectious Disease

Documentation Requirements

Detailed clinical notes on symptoms, lab results, and treatment plans.

Common Clinical Scenarios

Patients presenting with chronic abscesses or sinus tracts, especially in immunocompromised individuals.

Billing Considerations

Ensure clear documentation of the patient's immunocompromised status and any relevant comorbidities.

Pulmonology

Documentation Requirements

Radiological findings, pulmonary function tests, and treatment response.

Common Clinical Scenarios

Patients with thoracic actinomycosis presenting with respiratory symptoms.

Billing Considerations

Document any imaging studies that support the diagnosis and treatment decisions.

Coding Guidelines

Inclusion Criteria

Use A42.9 When
  • Follow the official ICD
  • CM coding guidelines for infectious diseases, ensuring accurate documentation of the site of infection and any underlying immunocompromised conditions

Exclusion Criteria

Do NOT use A42.9 When
No specific exclusions found.

Related CPT Codes

10060CPT Code

Incision and drainage of abscess

Clinical Scenario

Used when an abscess due to actinomycosis requires drainage.

Documentation Requirements

Document the size, location, and nature of the abscess.

Specialty Considerations

Infectious disease specialists should document the underlying cause of the abscess.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of actinomycosis, enabling better tracking of this infection and its complications. It has improved the granularity of data for epidemiological studies and healthcare planning.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of actinomycosis, enabling better tracking of this infection and its complications. It has improved the granularity of data for epidemiological studies and healthcare planning.

Reimbursement & Billing Impact

The transition to ICD-10 has allowed for more specific coding of actinomycosis, enabling better tracking of this infection and its complications. It has improved the granularity of data for epidemiological studies and healthcare planning.

Resources

Clinical References

  • •
    CDC Actinomycosis Information

Coding & Billing References

  • •
    CDC Actinomycosis Information

Frequently Asked Questions

What are the common symptoms of actinomycosis?

Common symptoms include swelling, pain, and the formation of abscesses in affected areas, often accompanied by fever and malaise.

How is actinomycosis diagnosed?

Diagnosis is typically made through clinical evaluation, imaging studies, and culture of the organism from infected tissue or pus.

What is the treatment for actinomycosis?

Treatment usually involves prolonged antibiotic therapy, often with penicillin, and may require surgical intervention for abscess drainage.