2026 ICD-10-CM Diagnosis Code K51.314Ulcerative (chronic) rectosigmoiditis with abscess

ICD-10-CM Codes›K00–K95›K50-K52›K51

ICD-10-CM K51.314
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K51.314 is a billable ICD-10-CM diagnosis code for ulcerative (chronic) rectosigmoiditis with abscess. 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 Peritonitis and intra-abdominal abscess and Regional enteritis and ulcerative colitis.

Code Identity

ICD-10-CM Code
K51.314
Billable Status
Yes — Valid for Submission
Code Describes
Ulcerative (chronic) rectosigmoiditis with abscess
Short Description
Ulcerative (chronic) rectosigmoiditis with abscess
Same as the full description in the CMS dataset.
Parent Code
K51.31
Ulcerative (chronic) rectosigmoiditis with complications

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK50-K52Noninfective enteritis and colitis
CategoryK51Ulcerative colitis
This CodeK51.314Ulcerative (chronic) rectosigmoiditis with abscess

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Abscess of intestine co-occurrent and due to chronic ulcerative proctitis
  • Abscess of intestine co-occurrent and due to chronic ulcerative rectosigmoiditis
  • Abscess of intestine co-occurrent and due to ulcerative colitis
  • Chronic left-sided ulcerative colitis
  • Chronic proctocolitis
  • Chronic ulcerative proctitis
  • Chronic ulcerative rectosigmoiditis
  • Complication due to chronic ulcerative proctitis
  • Complication due to chronic ulcerative rectosigmoiditis
  • Left sided ulcerative colitis
  • Proctocolitis
  • Proctosigmoiditis
  • Sigmoid colon ulcer
  • Ulcerative proctitis
  • Ulcerative proctocolitis

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.

    • Rectosigmoiditis
      • ulcerative (chronic)
        • with
          • complication
            • abscess

Clinical ClassificationClinical

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

CCSR DIG016
Peritonitis and intra-abdominal abscess
Default principal diagnosis: inpatient No · outpatient No
CCSR DIG011
Regional enteritis and ulcerative colitis
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Proctocolitis

    inflammation of the rectum and the distal portion of the colon.

  • Ulcerative Proctitis

    a form of ulcerative colitis where the inflammation is confined to the rectum.

  • Proctosigmoiditis

    inflammation of the sigmoid colon and rectum.

  • Proctocolitis

    inflammation of the rectum and colon.

Patient EducationClinical

Abscess

An abscess is a pocket of pus. You can get an abscess almost anywhere in your body. When an area of your body becomes infected, your body's immune system tries to fight the infection. White blood cells go to the infected area, collect within the damaged tissue, and cause inflammation. During this process, pus forms.

Read the full article at MedlinePlus

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

Convert K51.314 to ICD-9-CMHistory

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

ICD-9-CM
556.3 Ulcertve prctosigmoidtis
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
569.5 Intestinal abscess
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 K51.314Overview

Is K51.314 (Ulcerative (chronic) rectosigmoiditis with complications) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report ulcerative (chronic) rectosigmoiditis with abscess on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K51.314 group to?

When ulcerative (chronic) rectosigmoiditis with abscess 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 K51.314?

Under the General Equivalence Mappings, ulcerative (chronic) rectosigmoiditis with abscess converts to ICD-9-CM 556.3 (ulcertve prctosigmoidtis) and 569.5 (intestinal abscess). 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.