2027 ICD-10-CM Diagnosis Code A41.9Sepsis, unspecified organism

ICD-10-CM Codes›A00–B99›A30-A49›A41

ICD-10-CM A41.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

A41.9 is a billable ICD-10-CM diagnosis code for sepsis, unspecified organism. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 791, 793, 870 through 872, 974 through 976. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 46 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Septicemia.

For Medicare Advantage risk adjustment, A41.9 maps to CMS-HCC Category 2 (Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock) under the V28 model, adding a risk factor of about 0.500 for a community, non-dual, aged beneficiary in payment year 2027.

Code Identity

ICD-10-CM Code
A41.9
Billable Status
Yes — Valid for Submission
Code Describes
Sepsis, unspecified organism
Short Description
Sepsis, unspecified organism
Same as the full description in the CMS dataset.
Parent Code
A41
Other sepsis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA30-A49Other bacterial diseases
CategoryA41Other sepsis
This CodeA41.9Sepsis, unspecified organism

Medicare Risk Adjustment (HCC)Billing

A41.9 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.

CMS-HCC V28 Category (Payment Model)
HCC 2— Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock
Payment HCC · PY 2027 one of 52 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.500
community, non-dual, aged · ranges 0.447–0.780 across segments
Hierarchy
Top of its hierarchy
HCC 2 is not superseded by any other condition category
Prior Model (CMS-HCC V24)
HCC 2
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 2 · ESRD (V21): HCC 2 · ESRD (V24): HCC 2
ESRD V21 weights: 0.081 dialysis, 0.274–0.428 functioning graft · ESRD V24 weights: 0.087 dialysis, 0.270–0.532 functioning graft
Part D (RxHCC)
Not mapped
A41.9 does not risk-adjust in the RxHCC prescription drug model

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute kidney injury due to sepsis
  • Acute lung injury
  • Acute respiratory distress
  • Antepartum septicemia
  • Bacterial sepsis
  • Chronic kidney disease due to systemic infection
  • Clinical infection
  • Clinical sepsis
  • Encephalopathy with sepsis
  • Gastritis with sepsis
  • Gastrointestinal hemorrhage with sepsis
  • Gastrointestinal lesion with sepsis
  • Gastrointestinal ulcer due to sepsis
  • Indirect acute lung injury
  • Infection of blood and lymphatic system
  • Infection of bloodstream
  • Inflammation associated with vascular device
  • Left ventricular failure with sepsis
  • Lemierre syndrome
  • Lung injury with sepsis
  • Myocardial dysfunction with sepsis
  • Neutropenic sepsis
  • Postoperative sepsis
  • Pyemia
  • Respiratory distress
  • Right ventricular failure with sepsis
  • Sepsis
  • Sepsis associated with internal vascular access
  • Sepsis caused by central venous catheter in situ
  • Sepsis due to and following procedure
  • Sepsis due to oral infection
  • Sepsis due to urinary tract infection
  • Sepsis following infusion, injection, transfusion AND/OR vaccination
  • Sepsis in asplenic subject
  • Sepsis with acquired immunodeficiency syndrome
  • Sepsis with cutaneous manifestations
  • Sepsis without acute organ dysfunction
  • Sepsis without septic shock
  • Septic bronchitis
  • Septic splenitis
  • Septic thrombophlebitis
  • Septicemia associated with vascular access catheter
  • Splenitis
  • Systemic inflammatory response syndrome
  • Systemic inflammatory response syndrome without organ dysfunction
  • Thrombophlebitis of internal jugular vein
  • Thrombosis of internal jugular vein
  • Transient respiratory distress with sepsis

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to A41.9: its own notes plus those printed at A41 and Chapter 1. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • diseases generally recognized as communicable or transmissible

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Septicemia NOS

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From A41 Other sepsis applies to 15 codes

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From A41 Other sepsis applies to 15 codes
  • 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)
From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • carrier or suspected carrier of infectious disease (Z22.-)
  • certain localized infections - see body system-related chapters
  • infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
  • infectious and parasitic diseases specific to the perinatal period (P35-P39)
  • influenza and other acute respiratory infections (J00-J22)

Code First

The underlying condition named in the note is sequenced before this code.

From A41 Other sepsis applies to 15 codes

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • code to identify resistance to antimicrobial drugs (Z16.-)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name A41.9, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming A41.9: they are not reported together with it, unless the two conditions are unrelated.

  • A48.3 Toxic shock syndrome
    sepsis NOS (A41.9)

Code First 4

These codes say to code first a condition named in the note, and A41.9 is one of the conditions named.

  • R65.2 Severe sepsis
    sepsis NOS (A41.9)
  • I5A Non-ischemic myocardial injury (non-traumatic)
    sepsis (A41.-) names A41.-, which includes this code
  • N08 Glomerular disorders in diseases classified elsewhere
    sepsis (A40.0-A41.9) names A40.0-A41.9, which includes this code
  • N16 Renal tubulo-interstitial disorders in diseases classified elsewhere
    sepsis (A40.0-A41.9) names A40.0-A41.9, which includes this code

Use Additional Code 7

These codes say to use an additional code from the note, and A41.9 is one of the codes named.

  • T80.2 Infections following infusion, transfusion and therapeutic injection
    sepsis (A41.9)
  • J95.02 Infection of tracheostomy stoma
    sepsis (A40, A41.-) names A41.-, which includes this code
  • K94.02 Colostomy infection
    sepsis (A40.-, A41.-) names A41.-, which includes this code
  • K94.12 Enterostomy infection
    sepsis (A40.-, A41.-) names A41.-, which includes this code
  • K94.22 Gastrostomy infection
    sepsis (A40.-, A41.-) names A41.-, which includes this code
  • K95.01 Infection due to gastric band procedure
    sepsis (A40.-, A41.-) names A41.-, which includes this code
  • K95.81 Infection due to other bariatric procedure
    sepsis (A40.-, A41.-) names A41.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

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

Clinical InformationClinical

  • Sepsis

    systemic inflammatory response syndrome with a proven or suspected infectious etiology. when sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. when sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock.

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 A41.9 to ICD-9-CMHistory

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

ICD-9-CM
038.9 Septicemia NOS
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About A41.9Overview

What is the ICD-10 code for sepsis, unspecified organism?

The ICD-10-CM code for sepsis, unspecified organism is A41.9 (sometimes written as A419). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is A41.9 (Other sepsis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report sepsis, unspecified organism on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does A41.9 group to?

When sepsis, unspecified organism is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 974, 976, 872, 975, 871, 870, with relative weights from 0.7879 to 6.9432 depending on complications. Higher weights mean higher Medicare reimbursement.

Is A41.9 a CC or MCC?

CMS lists A41.9 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 46 closely related codes in its exclusion list.

Can A41.9 be reported with R78.81?

Not as a rule. The Excludes1 note at A41, which applies to A41.9, lists "bacteremia NOS (R78.81)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

What HCC is A41.9?

A41.9 (sepsis, unspecified organism) maps to CMS-HCC Category 2 (Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock), commonly written as HCC 2, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 2 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.

Does A41.9 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, A41.9 adds a risk adjustment factor of about 0.500 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.447 to 0.780 depending on the payment segment). HCC 2 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 2 category page.