2026 ICD-10-CM Diagnosis Code A40.9Streptococcal sepsis, unspecified

ICD-10-CM Codes›A00–B99›A30-A49›A40

ICD-10-CM A40.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A40.9 is a billable ICD-10-CM diagnosis code for streptococcal sepsis, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 870 through 872, 974 through 976. Coders also document this condition as sepsis caused by anaerobic bacteria. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Septicemia.

Code Identity

ICD-10-CM Code
A40.9
Billable Status
Yes — Valid for Submission
Code Describes
Streptococcal sepsis, unspecified
Short Description
Streptococcal sepsis, unspecified
Same as the full description in the CMS dataset.
Parent Code
A40
Streptococcal sepsis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA30-A49Other bacterial diseases
CategoryA40Streptococcal sepsis
This CodeA40.9Streptococcal sepsis, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Sepsis caused by anaerobic bacteria
  • Sepsis caused by anaerobic streptococcus
  • Sepsis caused by Streptococcus
  • Septic shock co-occurrent with acute organ dysfunction caused by Streptococcus
  • Septic shock co-occurrent with acute organ dysfunction due to Gram-positive coccus

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Disorder(of)
      • tubulo-interstitial (in)
        • sepsis
          • streptococcal
    • Embolism(multiple) (paradoxical)
      • pyemic (multiple)
        • streptococcal
    • Infection, infected, infective(opportunistic)
      • streptococcal NEC
        • generalized (purulent)
    • Sepsis(generalized) (unspecified organism)
      • Streptococcus, streptococcal

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INF003
Bacterial infections
Default principal diagnosis: inpatient No · outpatient No
CCSR INF002
Septicemia
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Sepsis

Sepsis is your body's overactive and extreme response to an infection. Sepsis is a life-threatening medical emergency. Without quick treatment, it can lead to tissue damage, organ failure, and even death.

The full article covers:

  • What is sepsis?
  • What causes sepsis?
  • Who is more likely to develop sepsis?
  • What are the symptoms of sepsis?
  • What other problems can sepsis cause?
  • How is sepsis diagnosed?
  • What are the treatments for sepsis?
  • Can sepsis be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert A40.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
038.0 Streptococcal septicemia
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
995.91 Sepsis
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About A40.9Overview

Is A40.9 (Streptococcal sepsis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report streptococcal sepsis, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does A40.9 group to?

When streptococcal sepsis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 870, 871, 872, 974, 975, 976, with relative weights from 0.8945 to 6.9118 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of A40.9?

Under the General Equivalence Mappings, streptococcal sepsis, unspecified converts to ICD-9-CM 038.0 (streptococcal septicemia) and 995.91 (sepsis). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.