2026 ICD-10-CM Diagnosis Code K81.9Cholecystitis, unspecified

ICD-10-CM Codes›K00–K95›K80-K87›K81

ICD-10-CM K81.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K81.9 is a billable ICD-10-CM diagnosis code for cholecystitis, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 444 through 446. Coders also document this condition as cholecystitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Biliary tract disease.

Code Identity

ICD-10-CM Code
K81.9
Billable Status
Yes — Valid for Submission
Code Describes
Cholecystitis, unspecified
Short Description
Cholecystitis, unspecified
Same as the full description in the CMS dataset.
Parent Code
K81
Cholecystitis

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK80-K87Disorders of gallbladder, biliary tract and pancreas
CategoryK81Cholecystitis
This CodeK81.9Cholecystitis, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Cholecystitis
  • Cholecystitis without calculus
  • Hyperplastic cholecystitis
  • Xanthogranulomatous cholecystitis

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.

    • Cholecystitis
    • Infection, infected, infective(opportunistic)
      • cystic duct

Clinical ClassificationClinical

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

CCSR DIG017
Biliary tract disease
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Acalculous Cholecystitis

    inflammation of the gallbladder wall in the absence of gallstones.

  • Cholecystitis

    inflammation of the gallbladder; generally caused by impairment of bile flow, gallstones in the biliary tract, infections, or other diseases.

  • Cholecystitis, Acute

    acute inflammation of the gallbladder wall. it is characterized by the presence of abdominal pain; fever; and leukocytosis. gallstone obstruction of the cystic duct is present in approximately 90% of the cases.

  • Emphysematous Cholecystitis

    a variant of acute cholecystitis with inflammation of the gallbladder that is characterized by the pockets of gas in the gallbladder wall. it is due to secondary infection caused by gas-forming organisms, and has a high risk of perforation.

  • Gallbladder

    a storage reservoir for bile secretion. gallbladder allows the delivery of bile acids at a high concentration and in a controlled manner, via the cystic duct to the duodenum, for degradation of dietary lipid.

  • Cholecystitis, CTCAE|Cholecystitis|Cholecystitis|Cholecystitis, CTCAE 5.0

    a disorder characterized by inflammation involving the gallbladder. it may be associated with the presence of gallstones.

  • Acalculous Cholecystitis

    inflammation of the gallbladder in the absence of gallstones.

  • Acute Acalculous Cholecystitis

    acute inflammation of the gallbladder in the absence of gallstones

  • Acute Cholecystitis

    acute inflammation of the gallbladder.

  • Cholecystitis

    an acute or chronic inflammation involving the gallbladder wall. it may be associated with the presence of gallstones.

  • Cholecystitis with Cholelithiasis

    an acute or chronic inflammation of the gallbladder associated with the presence of gallstones.

  • Cholecystitis, CTCAE 5.0|Cholecystitis|Cholecystitis

    a disorder characterized by inflammation involving the gallbladder. it may be associated with the presence of gallstones.

  • Chronic Acalculous Cholecystitis

    chronic cholecystitis not associated with the presence of gallstones.

  • Chronic Cholecystitis

    cholecystitis that is persistent and long-standing.

  • Emphysematous Cholecystitis

    cholecystitis resulting from infection by gas producing organisms.

  • Grade 2 Cholecystitis, CTCAE|Grade 2 Cholecystitis|Grade 2 Cholecystitis

    symptomatic; medical intervention indicated

  • Grade 3 Cholecystitis, CTCAE|Grade 3 Cholecystitis|Grade 3 Cholecystitis

    severe symptoms; invasive intervention indicated

  • Grade 4 Cholecystitis, CTCAE|Grade 4 Cholecystitis|Grade 4 Cholecystitis

    life-threatening consequences; urgent operative intervention indicated

  • Grade 5 Cholecystitis, CTCAE|Grade 5 Cholecystitis|Grade 5 Cholecystitis

    death

  • Xanthogranulomatous Cholecystitis

    cholecystitis that is characterized by nodules containing lipid.

Patient EducationClinical

Gallbladder Diseases

Your gallbladder is a pear-shaped organ under your liver. It stores bile, a fluid made by your liver to digest fat. As your stomach and intestines digest food, your gallbladder releases bile through a tube called the common bile duct. The duct connects your gallbladder and liver to your small intestine.

Read the full article at MedlinePlus

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

Convert K81.9 to ICD-9-CMHistory

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

ICD-9-CM
575.10 Cholecystitis NOS
Exact Match The mapping is direct, with no qualifiers.

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 K81.9Overview

Is K81.9 (Cholecystitis) a billable code?

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

What MS-DRG does K81.9 group to?

When cholecystitis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 444, 445, 446, with relative weights from 0.8273 to 1.6709 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K81.9?

Under the General Equivalence Mappings, cholecystitis, unspecified converts to ICD-9-CM 575.10 (cholecystitis NOS). The mapping is a direct match.

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.