2027 ICD-10-CM Diagnosis Code K65Peritonitis

ICD-10-CM Codes›K00–K95›K65-K6A›K65

ICD-10-CM K65
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

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
Short Description
Peritonitis
Same as the full description in the CMS dataset.
Chapter
K65-K6A
Diseases of peritoneum and retroperitoneum

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK65-K6ADiseases 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

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to K65: its own notes plus those printed at Chapter 11. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

  • 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.-)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 11 (K00-K95) Diseases of the digestive system applies to 863 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

  • code (B95-B97), to identify infectious agent, if known

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

  • if applicable diverticular disease of intestine (K57.-)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name K65, its category, or a range that includes it.

Code Also 1

These codes say K65 may also be needed to fully describe the condition. The note gives no sequencing direction.

  • K57 Diverticular disease of intestine
    peritonitis (K65.-)

Clinical InformationClinical

  • 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.

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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About K65Overview

What is the ICD-10 code for peritonitis?

K65 is the ICD-10-CM category for peritonitis, but it is a non-billable header: claims need a more specific code from this category, listed on this page.

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.

Can K65 be reported with a code from K35.2?

Not as a rule. The Excludes1 note on K65 lists "acute appendicitis with generalized peritonitis (K35.2-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

Does K65 need an additional code?

When the condition applies, yes. The Use Additional Code note reads: code (B95-B97), to identify infectious agent, if known. The additional code is reported after K65.