2026 ICD-10-CM Diagnosis Code K91.850Pouchitis

ICD-10-CM Codes›K00–K95›K90-K95›K91

ICD-10-CM K91.850
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K91.850 is a billable ICD-10-CM diagnosis code for pouchitis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 393 through 395. Coders also document this condition as chronic antibiotic-dependent ileal pouchitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Postprocedural or postoperative digestive system complication.

Code Identity

ICD-10-CM Code
K91.850
Billable Status
Yes — Valid for Submission
Code Describes
Pouchitis
Short Description
Pouchitis
Same as the full description in the CMS dataset.
Parent Code
K91.85
Complications of intestinal pouch

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK90-K95Other diseases of the digestive system
CategoryK91Intraoperative and postprocedural complications and disorders of digestive system, not elsewhere classified
This CodeK91.850Pouchitis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Chronic antibiotic-dependent ileal pouchitis
  • Chronic antibiotic-refractory pouchitis
  • Crohn-like disease of ileal pouch
  • Ileal pouchitis
  • Inflammation of ileoanal pouch

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Inflammation of internal ileoanal pouch

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.

    • Inflammation, inflamed, inflammatory(with exudation)
      • ileoanal (internal) pouch
    • Inflammation, inflamed, inflammatory(with exudation)
      • intestinal pouch
    • Pouchitis

Clinical ClassificationClinical

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

CCSR DIG024
Postprocedural or postoperative digestive system complication
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Pouchitis

    acute inflammation in the intestinal mucosa of the continent ileal reservoir (or pouch) in patients who have undergone ileostomy and restorative proctocolectomy (proctocolectomy, restorative).

Patient EducationClinical

After Surgery

After any operation, you'll have some side effects. There is usually some pain with surgery. There may also be swelling and soreness around the area that the surgeon cut. Your surgeon can tell you which side effects to expect.

Read the full article at MedlinePlus

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

Convert K91.850 to ICD-9-CMHistory

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

ICD-9-CM
569.71 Pouchitis
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 K91.850Overview

Is K91.850 (Complications of intestinal pouch) a billable code?

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

What MS-DRG does K91.850 group to?

When pouchitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 393, 394, 395, with relative weights from 0.6490 to 1.5993 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K91.850?

Under the General Equivalence Mappings, pouchitis converts to ICD-9-CM 569.71 (pouchitis). 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.