2026 ICD-10-CM Diagnosis Code K65.2Spontaneous bacterial peritonitis
ICD-10-CM Codes›K00–K95›K65-K68›K65
- Billable — Valid for Submission
- Not Chronic
K65.2 is a billable ICD-10-CM diagnosis code for spontaneous bacterial peritonitis. 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. Coders also document this condition as primary bacterial peritonitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Peritonitis and intra-abdominal abscess.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Primary bacterial peritonitis
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Type 1 Excludes
- bacterial peritonitis NOS K65.9
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
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.
- Peritonitis(adhesive) (bacterial) (fibrinous) (hemorrhagic) (idiopathic) (localized) (perforative) (primary) (with adhesions) (with effusion)
- spontaneous bacterial
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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.
Convert K65.2 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About K65.2Overview
Is K65.2 (Peritonitis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report spontaneous bacterial peritonitis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does K65.2 group to?
When spontaneous bacterial peritonitis 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 K65.2?
Under the General Equivalence Mappings, spontaneous bacterial peritonitis converts to ICD-9-CM 567.23 (spontan bact peritonitis). 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.
