2026 ICD-10-CM Diagnosis Code K85.91Acute pancreatitis with uninfected necrosis, unspecified

ICD-10-CM Codes›K00–K95›K80-K87›K85

ICD-10-CM K85.91
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K85.91 is a billable ICD-10-CM diagnosis code for acute pancreatitis with uninfected necrosis, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 438 through 440. Coders also document this condition as acute necrosis of pancreas. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Pancreatic disorders (excluding diabetes).

Code Identity

ICD-10-CM Code
K85.91
Billable Status
Yes — Valid for Submission
Code Describes
Acute pancreatitis with uninfected necrosis, unspecified
Short Description
Acute pancreatitis with uninfected necrosis, unspecified
Same as the full description in the CMS dataset.
Parent Code
K85.9
Acute pancreatitis, unspecified

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK80-K87Disorders of gallbladder, biliary tract and pancreas
CategoryK85Acute pancreatitis
This CodeK85.91Acute pancreatitis with uninfected necrosis, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute necrosis of pancreas
  • Acute necrotizing pancreatitis
  • Fat necrosis of subcutaneous tissue
  • Necrosis of pancreas
  • Necrosis of subcutaneous tissue
  • Nodular fat necrosis
  • Subcutaneous nodular fat necrosis in pancreatitis

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.

    • Pancreatitis(annular) (apoplectic) (calcareous) (edematous) (hemorrhagic) (malignant) (subacute) (suppurative)
      • with necrosis (uninfected)
    • Pancreatitis(annular) (apoplectic) (calcareous) (edematous) (hemorrhagic) (malignant) (subacute) (suppurative)
      • acute (without necrosis or infection)
        • with necrosis (uninfected)

Clinical ClassificationClinical

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

CCSR DIG020
Pancreatic disorders (excluding diabetes)
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Pancreatitis

The pancreas is a large gland behind the stomach and close to the first part of the small intestine. It secretes digestive juices into the small intestine through a tube called the pancreatic duct. The pancreas also releases the hormones insulin and glucagon into the bloodstream.

Read the full article at MedlinePlus

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

Convert K85.91 to ICD-9-CMHistory

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

ICD-9-CM
577.0 Acute pancreatitis
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement K85.91 replaces the following previously assigned code(s):

  • K85.9 - Acute pancreatitis, unspecified
FY 2018AddedAdded to the ICD-10-CM code setEffective October 1, 2017.
FY 2019–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K85.91Overview

Is K85.91 (Acute pancreatitis, unspecified) a billable code?

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

What MS-DRG does K85.91 group to?

When acute pancreatitis with uninfected necrosis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 438, 439, 440, with relative weights from 0.6214 to 1.6302 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K85.91?

Under the General Equivalence Mappings, acute pancreatitis with uninfected necrosis, unspecified converts to ICD-9-CM 577.0 (acute pancreatitis). 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.