2026 ICD-10-CM Diagnosis Code K65Peritonitis

ICD-10-CM Codes›K00–K95›K65-K68›K65

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

K65 is a non-billable ICD-10-CM category code for peritonitis, so it cannot be submitted on claims. Use a more specific code from this category instead, such as K65.0, K65.1, K65.2, and K65.3.

Code Identity

ICD-10-CM Code
K65
Billable Status
No — Non-Billable Category
Code Describes
Peritonitis
Chapter
K65-K68
Diseases of peritoneum and retroperitoneum

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK65-K68Diseases of peritoneum and retroperitoneum
CategoryK65Peritonitis
This CodeK65Peritonitis

Specific Coding for PeritonitisOverview

Non-specific codes like K65 require more characters. Use one of these billable codes instead:

  • Use K65.0 for Generalized (acute) peritonitis

  • Use K65.1 for Peritoneal abscess

  • Use K65.2 for Spontaneous bacterial peritonitis

  • Use K65.3 for Choleperitonitis

  • Use K65.4 for Sclerosing mesenteritis

  • Use K65.8 for Other peritonitis

  • Use K65.9 for Peritonitis, unspecified

Tabular List NotesGuidance

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

Code Also

  • if applicable diverticular disease of intestine K57

Use Additional Code

Type 1 Excludes

  • acute appendicitis with generalized peritonitis K35.2
  • aseptic peritonitis T81.6
  • benign paroxysmal peritonitis E85.0
  • chemical peritonitis T81.6
  • gonococcal peritonitis A54.85
  • neonatal peritonitis P78.0 P78.1
  • pelvic peritonitis, female N73.3 N73.5
  • periodic familial peritonitis E85.0
  • peritonitis due to talc or other foreign substance T81.6
  • peritonitis in chlamydia A74.81
  • peritonitis in diphtheria A36.89
  • peritonitis in syphilis late A52.74
  • peritonitis in tuberculosis A18.31
  • peritonitis with or following abortion or ectopic or molar pregnancy O00 O07 O08.0
  • peritonitis with or following appendicitis K35
  • puerperal peritonitis O85
  • retroperitoneal infections K68

Clinical InformationClinical

  • Chylous Ascites

    presence of milky lymph (chyle) in the peritoneal cavity, with or without infection.

  • Coronavirus, Feline

    a species of coronavirus infecting cats of all ages and commonly found in catteries and zoos. cats are often found carrying the virus but only a small proportion develop disease. feline coronavirus and feline infectious peritonitis virus (fipv) are virtually the same virus in genetic and antigenetic terms, and are morphologically indistinguishable. since they only differ in their disease potential (with fipv causing a more serious illness), they are considered biotypes of each other.

  • Familial Mediterranean Fever

    a group of hereditary autoinflammation diseases, characterized by recurrent fever, abdominal pain, headache, rash, pleurisy; and arthritis. orchitis; benign meningitis; and amyloidosis may also occur. homozygous or compound heterozygous mutations in marenostrin gene encoding pyrin result in autosomal recessive transmission; simple heterozygous, autosomal dominant form of the disease also exists with mutations in the same gene.

  • Feline Infectious Peritonitis

    common coronavirus infection of cats caused by the feline infectious peritonitis virus (coronavirus, feline). the disease is characterized by a long incubation period, fever, depression, loss of appetite, wasting, and progressive abdominal enlargement. infection of cells of the monocyte-macrophage lineage appears to be essential in fip pathogenesis.

  • Peritonitis

    inflammation of the peritoneum lining the abdominal cavity as the result of infectious, autoimmune, or chemical processes. primary peritonitis is due to infection of the peritoneal cavity via hematogenous or lymphatic spread and without intra-abdominal source. secondary peritonitis arises from the abdominal cavity itself through rupture or abscess of intra-abdominal organs.

  • Peritonitis, Tuberculous

    a form of peritonitis seen in patients with tuberculosis, characterized by lesion either as a miliary form or as a pelvic mass on the peritoneal surfaces. most patients have ascites, abdominal swelling, abdominal pain, and other systemic symptoms such as fever; weight loss; and anemia.

Patient EducationClinical

Peritoneal Disorders

Your peritoneum is the tissue that lines your abdominal wall and covers most of the organs in your abdomen. A liquid, peritoneal fluid, lubricates the surface of this tissue.

Read the full article at MedlinePlus

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

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 K65Overview

Is K65 (Peritonitis) a billable code?

No. This is a category header that groups the codes for peritonitis, and headers cannot be submitted on claims. Claims for peritonitis need a more specific code from this category, such as K65.0, K65.1, and K65.2.