A39.4 ICD-10-CM Code: Meningococcemia, unspecified
A39.4 maps to CMS-HCC V28 2. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software
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FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Other bacterial diseases (A30-A49)
A39.4
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceMeningococcemia, unspecified
A serious bloodstream infection caused by meningococcal bacteria (Neisseria meningitidis) where the specific type or severity is not specified. This condition can lead to sepsis and requires immediate medical treatment with antibiotics.
Buddy Insight
Meningococcemia, unspecified, captures Neisseria meningitidis bloodstream infection when the documentation does not specify whether the presentation is acute or chronic.
CMS-HCC V28
MappedHCC 2
Coefficient HCC 2: 0.500 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 002
Code-level coefficient reference
ESRD/PACE
MappedHCC 2
Code-level coefficient reference
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for A39.4. Check the code and parent instructions in the Code Book.
Excludes 2
Official- carrier or suspected carrier of infectious disease (Z22.-)Inherited from A00-B99
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)Inherited from A00-B99
- infectious and parasitic diseases specific to the perinatal period (P35-P39)Inherited from A00-B99
- influenza and other acute respiratory infections (J00-J22)Inherited from A00-B99
Related Codes
Includes
Official- diseases generally recognized as communicable or transmissibleInherited from A00-B99
Excludes 1
Official- certain localized infections - see body system-related chaptersInherited from A00-B99
Code First
OfficialNo Code First sequencing instructions are included in this display for A39.4. Check the code and parent instructions in the Code Book.
Use Additional
Official- code to identify resistance to antimicrobial drugs (Z16.-)Inherited from A00-B99
Code Also
OfficialNo Code Also instructions are included in this display for A39.4. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is A39.4 an HCC code?
Yes. A39.4 (Meningococcemia, unspecified) maps to HCC 2, Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.500. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.
Coder answer: A39.4 is billable and maps to V28 HCC 2, Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- A39.4
- Description
- Meningococcemia, unspecified
- HCC (V28)
- HCC 2 — Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock
- RAF reference coefficient
- 0.500
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.
Work A39.4 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for A39.4
For A39.4, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Coder workflow notes
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What This Code Means
A39.4 is the ICD-10-CM diagnosis code for meningococcemia, unspecified. A serious bloodstream infection caused by meningococcal bacteria (Neisseria meningitidis) where the specific type or severity is not specified. This condition can lead to sepsis and requires immediate medical treatment with antibiotics. A39.4 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering other bacterial diseases (a30-a49).
Under the CMS-HCC V28 risk adjustment model, A39.4 maps to Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock (HCC 2) with a source-labeled community, non-dual, aged reference coefficient of 0.500. No V24 mapping is shown for A39.4; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.
Use this code only when the documentation does not specify the type of meningococcemia (such as acute meningococcemia A39.2 or chronic meningococcemia A39.3); always review the clinical record to determine if a more specific code applies. For A39.4, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for A39.4 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when the documentation does not specify the type of meningococcemia (such as acute meningococcemia A39.2 or chronic meningococcemia A39.3); always review the clinical record to determine if a more specific code applies
- •This code indicates a systemic infection, so look for associated sepsis codes (R65.2x) or organ dysfunction codes that may need to be reported as secondary diagnoses
Clinical Significance
Meningococcemia, unspecified, captures Neisseria meningitidis bloodstream infection when the documentation does not specify whether the presentation is acute or chronic. While it maps to the same HCC as the specified forms, using this code represents a missed opportunity for clinical documentation precision.
Documentation Requirements
- ✓Blood cultures or clinical evidence of Neisseria meningitidis in the bloodstream
- ✓Documentation of meningococcal infection without specifying acute or chronic course
- ✓Clinical presentation and severity assessment
- ✓Query the provider to determine acute vs. chronic whenever possible to achieve higher specificity
- ✓Serogroup and antibiotic sensitivity if available
Commonly Confused Codes
- •A39.2 (Acute meningococcemia): Preferred code when acute presentation is documented; query provider before defaulting to unspecified
- •A39.3 (Chronic meningococcemia): Preferred code when chronic course is documented
- •A39.0 (Meningococcal meningitis): A39.4 is bloodstream infection; A39.0 is CNS infection: ensure correct site is coded