A41.51
BillableSepsis due to Escherichia coli [E. coli]
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is A41.51 an HCC code?
Yes. A41.51 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 A41.51
For A41.51 to 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 A41.51 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
A41.51 is the ICD-10-CM diagnosis code for sepsis due to escherichia coli [e. coli]. A serious bloodstream infection caused by E. coli bacteria that has spread throughout the body, causing a severe inflammatory response. This is a life-threatening condition that requires immediate medical treatment. A41.51 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, A41.51 maps to Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock (HCC 2) with a community, non-dual, aged base RAF weight of 0.455. The V24 model used during the PY2024–PY2025 transition mapped A41.51 the same way and at the same RAF weight. 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.
Always verify the organism (E. coli) is documented in the medical record before assigning this code; sepsis requires both the systemic inflammatory response and confirmed organism identification. Because A41.51 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 A41.51 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Always verify the organism (E. coli) is documented in the medical record before assigning this code; sepsis requires both the systemic inflammatory response and confirmed organism identification
- •This code should be paired with a code for the severity of sepsis (such as R65.20 for sepsis without acute organ dysfunction or R65.21 for sepsis with acute organ dysfunction) to provide complete clinical documentation
Clinical Significance
Sepsis due to Escherichia coli is the most common cause of gram-negative sepsis, typically arising from urinary tract infections, intra-abdominal infections, or biliary tract disease. E. coli sepsis is a major cause of urosepsis in the elderly and is increasingly complicated by multidrug-resistant strains (ESBL-producing E. coli).
Documentation Requirements
- ✓Blood cultures positive for Escherichia coli
- ✓Source of E. coli infection identified and documented (UTI, cholangitis, intra-abdominal abscess, spontaneous bacterial peritonitis)
- ✓Antibiotic susceptibility results, particularly ESBL status
- ✓Sepsis severity: organ dysfunction, vasopressor requirements, lactate levels
- ✓Underlying risk factors documented (urinary obstruction, biliary disease, cirrhosis, diabetes)
Commonly Confused Codes
- •A41.50 (Gram-negative sepsis, unspecified) — Use A41.51 when E. coli is specifically identified, not the unspecified gram-negative code
- •A41.59 (Other gram-negative sepsis) — A41.59 is for gram-negative organisms other than E. coli, Pseudomonas, Serratia, and Acinetobacter
- •N39.0 (Urinary tract infection, site not specified) — Code the UTI source separately alongside the sepsis code