2026 ICD-10-CM Diagnosis Code K65.1Peritoneal abscess

ICD-10-CM Codes›K00–K95›K65-K68›K65

ICD-10-CM K65.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K65.1 is a billable ICD-10-CM diagnosis code for peritoneal abscess. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 371 through 373. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Peritonitis and intra-abdominal abscess.

Code Identity

ICD-10-CM Code
K65.1
Billable Status
Yes — Valid for Submission
Code Describes
Peritoneal abscess
Short Description
Peritoneal abscess
Same as the full description in the CMS dataset.
Parent Code
K65
Peritonitis

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK65-K68Diseases of peritoneum and retroperitoneum
CategoryK65Peritonitis
This CodeK65.1Peritoneal abscess

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Abdominal abscess
  • Abdominal visceral abscess
  • Abdominopelvic abscess
  • Abscess between intestinal loops
  • Abscess due to peritonitis
  • Abscess of abdomen caused by Nocardia
  • Abscess of adrenal gland
  • Abscess of omentum
  • Abscess of peritoneum
  • Abscess of Rutherford Morison pouch
  • Acute male pelvic abscess
  • Intradiaphragmatic abscess
  • Lesser sac abscess
  • Male pelvic abscess
  • Mesenteric abscess
  • Midabdominal abscess
  • Paracolic abscess
  • Pelvic abscess
  • Peritonitis due to abscess
  • Postoperative intra-abdominal abscess
  • Postprocedural intraabdominal abscess
  • Retrocecal abscess
  • Retroperitoneal abscess
  • Subdiaphragmatic abscess
  • Subhepatic abscess
  • Subperitoneal abscess
  • Suprahepatic abscess

Tabular List NotesGuidance

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

Inclusion Terms

  • Abdominopelvic abscess
  • Abscess (of) omentum
  • Abscess (of) peritoneum
  • Mesenteric abscess
  • Retrocecal abscess
  • Subdiaphragmatic abscess
  • Subhepatic abscess
  • Subphrenic abscess

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)
      • abdomen, abdominal
        • cavity
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • abdominopelvic
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • diaphragm, diaphragmatic
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • epiploon, epiploic
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • intra-abdominal
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • intraperitoneal
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • mesentery, mesenteric
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • omentum
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • pelvis, pelvic
        • male, peritoneal
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • peritoneum, peritoneal (perforated) (ruptured)
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • peritoneum, peritoneal (perforated) (ruptured)
        • pelvic
          • male
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • retrocecal
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • subdiaphragmatic
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • subhepatic
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • subphrenic
    • Peritonitis(adhesive) (bacterial) (fibrinous) (hemorrhagic) (idiopathic) (localized) (perforative) (primary) (with adhesions) (with effusion)
      • with or following
        • abscess
    • Sepsis(generalized) (unspecified organism)
      • intra-abdominal

Clinical ClassificationClinical

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

CCSR DIG016
Peritonitis and intra-abdominal abscess
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Abdominal Abscess

    an abscess located in the abdominal cavity, i.e., the cavity between the diaphragm above and the pelvis below. (from dorland, 27th ed)

  • Pelvic Abscess

    an abscess that is located in the pelvic cavity.

  • Mesenteric Abscess

    an abscess that is located in any part of the tissue composing the mesentery, and that generally arises from an infection in an adjacent area of the intestine.

  • Retroperitoneal Abscess

    an abscess that is located in the abdominal cavity posterior to the peritoneum.

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 K65.1 to ICD-9-CMHistory

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

ICD-9-CM
567.22 Peritoneal abscess
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 K65.1Overview

Is K65.1 (Peritonitis) a billable code?

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

What MS-DRG does K65.1 group to?

When peritoneal abscess is the principal diagnosis on an inpatient stay, it groups to MS-DRG 371, 372, 373, with relative weights from 0.7274 to 1.7731 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K65.1?

Under the General Equivalence Mappings, peritoneal abscess converts to ICD-9-CM 567.22 (peritoneal abscess). 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.