A41.9 Sepsis, unspecified organism

The ICD-10-CM code for Sepsis, unspecified organism is A41.9 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

1: Certain infectious and parasitic diseases (A00-B99)

Section

A30-A49: Other bacterial diseases (A30-A49)

Category A41

19 codes (15 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to A41.9:

• Sepsis (generalized) (unspecified organism)
• Septicemia
• Sepsis (generalized) (unspecified organism) › cryptogenic
• Sepsis (generalized) (unspecified organism) › gangrenous
• Disorder (of) › tubulo-interstitial (in) › sepsis
• Glomerulonephritis › in (due to) › sepsis
• Pyelonephritis › in (due to) › sepsis

Inclusion Terms

• Septicemia NOS

U.S. Hospital Utilization

• An estimated 2,187,520 U.S. inpatient stays in 2023 included A41.9 among the documented diagnoses.
• 1,770,020 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Prevalence & Statistics

• Each year, at least 1.7 million adults in the United States develop sepsis. (CDC — About Sepsis (based on Rhee et al., JAMA 2017, US Hospitals 2009–2014), 2014)

Official Coding Guidelines

Sepsis: underlying systemic infection code; default A41.9; R65.2 rule

For a diagnosis of sepsis, assign the appropriate code for the underlying systemic infection. If the type of infection or causal organism is not further specified, assign code A41.9, Sepsis, unspecified organism. A code from subcategory R65.2, Severe sepsis, should not be assigned unless severe sepsis or an associated acute organ dysfunction is documented.

Severe sepsis—minimum codes and sequencing basics

(b) Severe sepsis The coding of severe sepsis requires a minimum of 2 codes: first a code for the underlying systemic infection, followed by a code from subcategory R65.2, Severe sepsis. If the causal organism is not documented, assign code A41.9, Sepsis, unspecified organism, for the infection. Additional code(s) for the associated acute organ dysfunction are also required. Due to the complex nature of severe sepsis, some cases may require querying the provider prior to assignment of the codes.

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)
• CDC — About Sepsis (based on Rhee et al., JAMA 2017, US Hospitals 2009–2014) (2014)