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ICD-10-CM A41.9: Sepsis, unspecified organism

A41.9 is the billable ICD-10-CM code for sepsis, unspecified organism, in category A41 (Other sepsis) of the Other bacterial diseases section. As a principal diagnosis it groups to MS-DRG 791 Prematurity with Major Problems, MS-DRG 793 Full Term Neonate with Major Problems (MDC 15 MDC 15: Newborns and Other Neonates with Conditions Originating in Perinatal Period); or MS-DRG 870 Septicemia or Severe Sepsis with MV >96 Hours, MS-DRG 871 Septicemia or Severe Sepsis without MV >96 Hours with MCC, MS-DRG 872 Septicemia or Severe Sepsis without MV >96 Hours without MCC (MDC 18 MDC 18: Infectious and Parasitic Diseases, Systemic or Unspecified Sites). It maps to HCC 2 (Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock) in CMS-HCC V28. As a secondary diagnosis it is an MCC, excluded with 46 principal diagnoses. 15 LCD billing and coding articles list it as covered.

Compiled from CMS files by the QuickIntell RCM Editorial Team · Data effective · Method: reference methodology · Report a data correction

Data currency: ICD-10-CM code descriptions: FY2027 (effective October 1, 2026); IPPS Table 5 (MS-DRG weights): v44 FY2027 (final rule + CN3) (effective October 1, 2026); ICD-10-CM to HCC mapping: PY2027 initial ICD-10-CM mappings (dates of service 2026) (payment year 2027); Medicare Coverage Database billing and coding articles: MCD release October 8, 2026 (effective October 4, 2026). Next CMS release: FY2028 code files, effective October 1, 2027 for the ICD-10-CM code descriptions; FY2028 final rule (August 2027), effective October 1, 2027; an April 1 interim grouper update when CMS issues one for the IPPS Table 5 (MS-DRG weights); PY2028 advance notice (February 2027) and the PY2027 midyear final mapping (spring 2027) for the ICD-10-CM to HCC mapping; weekly, every Thursday for the Medicare Coverage Database billing and coding articles.

Code
A41.9
billable FY2027 ICD-10-CM code
Category
A41 Other sepsis
Chapter
1: Certain infectious and parasitic diseases (A00-B99)
CC/MCC (MS-DRG v44)
MCC
CMS-HCC V28
HCC 2
POA reporting
Required

Tabular list notes for A41.9

Inclusion terms
  • Septicemia NOS

Inherited from A41 (Other sepsis)

Excludes1 (never coded together)
  • bacteremia NOS (R78.81)
  • neonatal (P36.-)
  • puerperal sepsis (O85)
  • streptococcal sepsis (A40.-)
Excludes2 (not part of this condition, may be coded together)
  • sepsis (due to) (in) actinomycotic (A42.7)
  • sepsis (due to) (in) anthrax (A22.7)
  • sepsis (due to) (in) candidal (B37.7)
  • sepsis (due to) (in) Erysipelothrix (A26.7)
  • sepsis (due to) (in) extraintestinal yersiniosis (A28.2)
  • sepsis (due to) (in) gonococcal (A54.86)
  • sepsis (due to) (in) herpesviral (B00.7)
  • sepsis (due to) (in) listerial (A32.7)
  • sepsis (due to) (in) melioidosis (A24.1)
  • sepsis (due to) (in) meningococcal (A39.2-A39.4)
  • sepsis (due to) (in) plague (A20.7)
  • sepsis (due to) (in) tularemia (A21.7)
  • toxic shock syndrome (A48.3)
Code first
  • , if applicable, postprocedural sepsis (T81.44-)
  • sepsis due to central venous catheter (T80.211-)
  • sepsis during labor (O75.3)
  • sepsis following abortion, ectopic or molar pregnancy (O03.37, O03.87, O04.87, O07.37, O08.82)
  • sepsis following immunization (T88.0-)
  • sepsis following infusion, transfusion or therapeutic injection (T80.22-, T80.29-)

MS-DRG grouping when A41.9 is the principal diagnosis

MS-DRG v44 groups for A41.9 as principal diagnosis
MDCMS-DRGs
15 MDC 15: Newborns and Other Neonates with Conditions Originating in Perinatal Period791793
18 MDC 18: Infectious and Parasitic Diseases, Systemic or Unspecified Sites870871872
25 MDC 25: Human Immunodeficiency Virus Infections974975976

The final group also depends on procedures, secondary diagnoses and discharge status; the MS-DRG lookup for A41.9 shows the full grouping logic.

CC/MCC status and inpatient edits

As a secondary diagnosis, A41.9 is an MCC under MS-DRG v44, unless the principal diagnosis is one of the 46 codes in its exclusion list. Check A41.9 against a principal diagnosis.

  • Present on admission: a POA indicator is required on inpatient claims.

CMS-HCC V28 risk adjustment

In the PY2027 mapping, A41.9 maps to HCC 2 (Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock). The HCC lookup shows the RAF weight and the hierarchy.

LCD billing and coding articles that list A41.9

15 current Medicare billing and coding articles list A41.9 among the diagnoses that support medical necessity for the services they cover.

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Frequently asked questions

What does ICD-10-CM A41.9 mean?

A41.9 means sepsis, unspecified organism. The tabular list also files these terms under it: Septicemia NOS. It is one of 15 billable codes under A41, other sepsis.

What can't be coded with A41.9?

Excludes1 at A41: bacteremia NOS (R78.81); neonatal (P36.-); puerperal sepsis (O85); streptococcal sepsis (A40.-). These are never reported together with A41.9.

Which MS-DRG does A41.9 group to?

As the principal diagnosis, A41.9 groups to MS-DRG 791 Prematurity with Major Problems, MS-DRG 793 Full Term Neonate with Major Problems (MDC 15 MDC 15: Newborns and Other Neonates with Conditions Originating in Perinatal Period); or MS-DRG 870 Septicemia or Severe Sepsis with MV >96 Hours, MS-DRG 871 Septicemia or Severe Sepsis without MV >96 Hours with MCC, MS-DRG 872 Septicemia or Severe Sepsis without MV >96 Hours without MCC (MDC 18 MDC 18: Infectious and Parasitic Diseases, Systemic or Unspecified Sites) under MS-DRG v44, before procedures and secondary diagnoses are applied.

Does A41.9 map to an HCC?

Yes: HCC 2, Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock, in the PY2027 CMS-HCC V28 mapping.

Is A41.9 a CC or MCC?

A41.9 is an MCC under MS-DRG v44; 46 principal diagnoses exclude it.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Disclaimer

The descriptor and notes are reproduced from the FY2027 ICD-10-CM files; MS-DRG, CC/MCC and HCC facts come from the CMS FY2027 and PY2027 tables. Code from the medical record and the ICD-10-CM Official Guidelines. Not legal, clinical or billing advice.

Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.