A41.53
BillableSepsis due to Serratia
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is A41.53 an HCC code?
Yes. A41.53 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 A41.53
For A41.53to 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 A41.53 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
A41.53 is the ICD-10-CM diagnosis code for sepsis due to serratia. This is a serious bloodstream infection caused by Serratia bacteria, a type of gram-negative organism commonly found in healthcare settings. The infection spreads throughout the body and can cause organ failure and shock if not treated promptly. A41.53 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, A41.53 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, A41.53 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.
Always verify that sepsis is documented in the medical record before coding A41.53; sepsis requires systemic inflammatory response to confirmed infection. Because A41.53 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 A41.53 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Always verify that sepsis is documented in the medical record before coding A41.53; sepsis requires systemic inflammatory response to confirmed infection
- •Check for associated organ dysfunction codes (such as acute kidney injury, acute respiratory distress syndrome) that should be coded separately to capture the full severity of the condition
Clinical Significance
Sepsis due to Serratia is a healthcare-associated gram-negative bloodstream infection caused by Serratia marcescens. It is notorious for contaminating medical equipment, IV fluids, and respiratory therapy devices. Serratia is intrinsically resistant to many first-line antibiotics, including ampicillin and first-generation cephalosporins, requiring targeted therapy.
Documentation Requirements
- ✓Blood cultures positive for Serratia species (typically S. marcescens)
- ✓Healthcare-associated infection assessment and documentation
- ✓Source of infection (central line, respiratory equipment, urinary catheter, contaminated medication)
- ✓Antibiotic susceptibility results documenting resistance pattern
- ✓Infection control investigation if outbreak is suspected
Commonly Confused Codes
- •A41.50 (Gram-negative sepsis, unspecified) — Use A41.53 when Serratia is specifically identified
- •A41.59 (Other gram-negative sepsis) — A41.53 has its own specific code; do not use the 'other' category for Serratia
- •A41.51 (Sepsis due to E. coli) — Both are Enterobacteriaceae but different organisms requiring different antibiotic approaches