2026 ICD-10-CM Diagnosis Code K57.21Diverticulitis of large intestine with perforation and abscess with bleeding

ICD-10-CM Codes›K00–K95›K55-K64›K57

ICD-10-CM K57.21
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K57.21 is a billable ICD-10-CM diagnosis code for diverticulitis of large intestine with perforation and abscess with bleeding. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 377 through 379. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Diverticulosis and diverticulitis, Gastrointestinal and biliary perforation, and Gastrointestinal hemorrhage.

Code Identity

ICD-10-CM Code
K57.21
Billable Status
Yes — Valid for Submission
Code Describes
Diverticulitis of large intestine with perforation and abscess with bleeding
Short Description
Dvtrcli of lg int w perforation and abscess w bleeding
Parent Code
K57.2
Diverticulitis of large intestine with perforation and abscess

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK55-K64Other diseases of intestines
CategoryK57Diverticular disease of intestine
This CodeK57.21Diverticulitis of large intestine with perforation and abscess with bleeding

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.

    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • with
        • diverticular disease (intestine)
          • large intestine
            • with
              • bleeding
    • Diverticulitis(acute)
      • intestine
        • large
          • with
            • abscess, perforation
              • with bleeding
    • Perforation, perforated(nontraumatic) (of)
      • diverticulum (intestine)
        • large intestine
          • with
            • bleeding
    • Peritonitis(adhesive) (bacterial) (fibrinous) (hemorrhagic) (idiopathic) (localized) (perforative) (primary) (with adhesions) (with effusion)
      • with or following
        • diverticular disease (intestine)
          • large intestine
            • with
              • bleeding
    • Rupture, ruptured
      • diverticulum (intestine)
        • large intestine
          • with
            • bleeding

Clinical ClassificationClinical

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

CCSR DIG013
Diverticulosis and diverticulitis
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR DIG006
Gastrointestinal and biliary perforation
Default principal diagnosis: inpatient No · outpatient No
CCSR DIG021
Gastrointestinal hemorrhage
Default principal diagnosis: inpatient No · outpatient No

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 K57.21 to ICD-9-CMHistory

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

ICD-9-CM
562.13 Dvrtcli colon w hmrhg
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 K57.21Overview

Is K57.21 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report diverticulitis of large intestine with perforation and abscess with bleeding on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K57.21 group to?

When diverticulitis of large intestine with perforation and abscess with bleeding is the principal diagnosis on an inpatient stay, it groups to MS-DRG 377, 378, 379, with relative weights from 0.6304 to 1.8280 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K57.21?

Under the General Equivalence Mappings, diverticulitis of large intestine with perforation and abscess with bleeding converts to ICD-9-CM 562.13 (dvrtcli colon w hmrhg) 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.