A04.3 ICD-10-CM Code: Enterohemorrhagic Escherichia coli infection
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FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Intestinal infectious diseases (A00-A09)
A04.3
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceEnterohemorrhagic Escherichia coli infection
This is a serious bacterial infection caused by a specific strain of E. coli that produces toxins and causes bloody diarrhea and severe abdominal cramping. It can lead to serious complications like kidney failure, especially in young children and elderly patients.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for A04.3 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for A04.3 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for A04.3 in this effective period.
Excludes 1
Official- bacterial foodborne intoxications, NEC (A05.-)
- tuberculous enteritis (A18.32)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for A04.3 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for A04.3 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for A04.3 in this effective period.
Buddy Documentation Tip
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 A04.3 an HCC code?
No. A04.3 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
- Code
- A04.3
- Description
- Enterohemorrhagic Escherichia coli infection
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF
- —
- Billable
- Yes
- Payment year
- 2026
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
A04.3 is the ICD-10-CM diagnosis code for enterohemorrhagic escherichia coli infection. This is a serious bacterial infection caused by a specific strain of E. coli that produces toxins and causes bloody diarrhea and severe abdominal cramping. It can lead to serious complications like kidney failure, especially in young children and elderly patients. A04.3 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering intestinal infectious diseases (a00-a09).
A04.3 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Verify the specific E. coli strain (O157:H7 is most common) is documented in the medical record, as this helps confirm the enterohemorrhagic type rather than other pathogenic E. coli strains.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for A04.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify the specific E. coli strain (O157:H7 is most common) is documented in the medical record, as this helps confirm the enterohemorrhagic type rather than other pathogenic E. coli strains
- •Look for documentation of hemolytic uremic syndrome (HUS) or other complications, as these may require additional codes (D59.3 for HUS) and affect severity assessment