A41.50
BillableGram-negative sepsis, unspecified
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is A41.50 an HCC code?
Yes. A41.50 maps to Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock under the CMS-HCC V28 risk adjustment model (and Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for A41.50
For A41.50to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- 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
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed A41.50 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
A41.50 is the ICD-10-CM diagnosis code for gram-negative sepsis, unspecified. This code describes a serious bloodstream infection caused by gram-negative bacteria where the specific type of bacteria has not been identified. Gram-negative bacteria are a common cause of life-threatening infections that require immediate treatment with antibiotics. A41.50 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, A41.50 maps to Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock (HCC 2) with a community, non-dual, aged base RAF weight of 0.500. Under the older V24 model, A41.50 mapped to the same category but with a base RAF weight of 0.352 — V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Use this code only when the gram-negative organism is not specified; if the specific organism is identified (such as E. coli, Pseudomonas, or Klebsiella), use the more specific subcategory codes A41.51-A41.59. Because A41.50 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. 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, RAF weights, and MEAT documentation criteria for A41.50 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 gram-negative organism is not specified; if the specific organism is identified (such as E. coli, Pseudomonas, or Klebsiella), use the more specific subcategory codes A41.51-A41.59
- •Sepsis codes require documentation of the systemic inflammatory response; ensure the clinical record clearly documents sepsis diagnosis and consider querying the provider if only bacteremia or infection is documented without sepsis criteria
Clinical Significance
Gram-negative sepsis, unspecified, captures bloodstream infection by an unidentified gram-negative organism. Gram-negative sepsis is associated with higher rates of septic shock due to endotoxin (lipopolysaccharide) release. This unspecified code should be updated when culture identification is available.
Documentation Requirements
- ✓Gram stain of blood cultures showing gram-negative organisms, or clinical documentation of gram-negative sepsis
- ✓Sepsis criteria documented with organ dysfunction assessment
- ✓Pending culture identification noted in documentation
- ✓Source of suspected gram-negative infection (urinary tract, intra-abdominal, respiratory, biliary)
- ✓Empiric antibiotic coverage for gram-negative organisms documented
Commonly Confused Codes
- •A41.51 (Sepsis due to E. coli) — Preferred when E. coli is specifically identified
- •A41.52 (Sepsis due to Pseudomonas) — Preferred when Pseudomonas is identified
- •A41.59 (Other gram-negative sepsis) — Use when a specific gram-negative organism is identified but does not have its own code
- •A41.9 (Sepsis, unspecified organism) — A41.50 is more specific than A41.9 since it at least identifies gram-negative morphology