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v1.0.0
ICD-10 Guide
ICD-10 CodesA40.9

A40.9

Sepsis, unspecified organism

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

Code Description

ICD-10 A40.9 is a billable code used to indicate a diagnosis of sepsis, unspecified organism.

Key Diagnostic Point:

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. The condition can arise from various infections, including bacterial, viral, or fungal origins, but when the specific organism is not identified, it is coded as A40.9. Clinically, sepsis presents with symptoms such as fever, increased heart rate, rapid breathing, and altered mental status. Severe cases may lead to septic shock, characterized by persistent hypotension despite adequate fluid resuscitation. Patients with sepsis often require intensive care unit (ICU) admission for close monitoring and aggressive management, including intravenous fluids, vasopressors, and broad-spectrum antibiotics. Antimicrobial stewardship is crucial in managing sepsis to ensure appropriate antibiotic use, minimizing resistance, and optimizing patient outcomes. Early recognition and treatment are vital, as delays can significantly increase morbidity and mortality rates. The coding of sepsis, particularly when the organism is unspecified, requires careful documentation of clinical findings and treatment interventions to support the diagnosis and ensure accurate reimbursement.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variability in clinical presentation and severity of sepsis.
  • Need for thorough documentation to support the diagnosis.
  • Differentiation from other similar conditions (e.g., septic shock).
  • Potential for multiple underlying infections complicating coding.

Audit Risk Factors

  • Inadequate documentation of clinical findings.
  • Failure to specify the source of infection.
  • Inconsistent coding of sepsis severity.
  • Lack of evidence for the necessity of ICU admission.

Specialty Focus

Medical Specialties

Infectious Disease

Documentation Requirements

Detailed history of infection, laboratory results, and treatment response.

Common Clinical Scenarios

Patients presenting with fever and signs of systemic infection.

Billing Considerations

Documentation must clearly indicate the absence of identified organisms.

Critical Care Medicine

Documentation Requirements

Comprehensive ICU admission notes, including vital signs and treatment protocols.

Common Clinical Scenarios

Patients requiring mechanical ventilation or vasopressor support.

Billing Considerations

Clear documentation of organ dysfunction and response to treatment is essential.

Coding Guidelines

Inclusion Criteria

Use A40.9 When
  • According to ICD
  • 10 guidelines, A40
  • 9 should be used when the specific organism causing sepsis is not identified
  • Coders must ensure that the documentation supports the diagnosis of sepsis and any associated organ dysfunction

Exclusion Criteria

Do NOT use A40.9 When
No specific exclusions found.

Related CPT Codes

99223CPT Code

Initial hospital care, typically 70 minutes or more

Clinical Scenario

Used for patients admitted with sepsis requiring extensive evaluation.

Documentation Requirements

Comprehensive history, examination, and medical decision-making.

Specialty Considerations

Critical care specialists should document the severity of illness.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of sepsis, improving the granularity of data collection and reimbursement processes. A40.9 serves as a catch-all for unspecified cases, emphasizing the need for thorough documentation.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of sepsis, improving the granularity of data collection and reimbursement processes. A40.9 serves as a catch-all for unspecified cases, emphasizing the need for thorough documentation.

Reimbursement & Billing Impact

reimbursement processes. A40.9 serves as a catch-all for unspecified cases, emphasizing the need for thorough documentation.

Resources

Clinical References

  • •
    CDC Sepsis Guidelines

Coding & Billing References

  • •
    CDC Sepsis Guidelines

Frequently Asked Questions

When should I use A40.9?

A40.9 should be used when a patient is diagnosed with sepsis, but the specific organism causing the infection has not been identified. Ensure that documentation supports the diagnosis and any associated organ dysfunction.