2026 ICD-10-CM Diagnosis Code K51.813Other ulcerative colitis with fistula

ICD-10-CM Codes›K00–K95›K50-K52›K51

ICD-10-CM K51.813
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K51.813 is a billable ICD-10-CM diagnosis code for other ulcerative colitis with fistula. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 385 through 387. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Regional enteritis and ulcerative colitis.

Code Identity

ICD-10-CM Code
K51.813
Billable Status
Yes — Valid for Submission
Code Describes
Other ulcerative colitis with fistula
Short Description
Other ulcerative colitis with fistula
Same as the full description in the CMS dataset.
Parent Code
K51.81
Other ulcerative colitis with complications

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK50-K52Noninfective enteritis and colitis
CategoryK51Ulcerative colitis
This CodeK51.813Other ulcerative colitis with fistula

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.

    • Colitis(acute) (catarrhal) (chronic) (noninfective) (hemorrhagic)
      • ulcerative (chronic)
        • specified type NEC
          • with
            • complication
              • fistula

Clinical ClassificationClinical

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

CCSR DIG011
Regional enteritis and ulcerative colitis
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Fistulas

A fistula is an abnormal connection between two parts inside of the body. Fistulas may develop between different organs, such as between the esophagus and the windpipe or the bowel and the vagina. They can also develop between two blood vessels, such as between an artery and a vein or between two arteries.

Read the full article at MedlinePlus

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

Convert K51.813 to ICD-9-CMHistory

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

ICD-9-CM
556.8 Other ulcerative colitis
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
569.81 Intestinal fistula
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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K51.813Overview

Is K51.813 (Other ulcerative colitis with complications) a billable code?

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

What MS-DRG does K51.813 group to?

When other ulcerative colitis with fistula is the principal diagnosis on an inpatient stay, it groups to MS-DRG 385, 386, 387, with relative weights from 0.6813 to 1.5823 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K51.813?

Under the General Equivalence Mappings, other ulcerative colitis with fistula converts to ICD-9-CM 556.8 (other ulcerative colitis) and 569.81 (intestinal fistula). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.