ICD-10-CM 2027 diagnosis code

K65Peritonitis

Not billable — use a more specific code

K65 is a header code, so it can't be reported by itself. Choose one of the 7 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About K65

K65 is the ICD-10-CM diagnosis code for peritonitis. It belongs to block K65-K6A (diseases of peritoneum, retroperitoneum and pelvis) and chapter 11 (diseases of the digestive system). It is a header code, so it can't be reported by itself; one of its 7 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: K65.0 (peritonitis), K65.1 (abscess), K65.2 (peritonitis), K65.3 (Choleperitonitis), K65.4 (mesenteritis), K65.8 (peritonitis) and K65.9 (unspecified).

Don't report K65 together with the conditions in its Excludes1 note: acute appendicitis with generalized peritonitis (K35.2-), aseptic peritonitis (T81.6), benign paroxysmal peritonitis (E85.0), chemical peritonitis (T81.6) and 13 more.

Use an additional code (B95-B97), to identify infectious agent, if known.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under K65

Coding notes

Excludes1Not coded here — never report together with this code

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.-)

Use additional codeAdd a secondary code to fully describe the condition

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

Code alsoTwo codes may be needed; sequencing depends on circumstances

if applicable diverticular disease of intestine (K57.-)

Notes that apply from higher levels

Instructions written at a parent level also apply to K65.

Broader instructions also apply from Chapter 11: Diseases of the digestive system.

Codes whose notes reference K65

K57Code also

Code history

2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027

FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
No changes since FY2016.

Common questions about K65

Is K65 billable?: No. K65 is a header code. Report one of its more specific subcodes instead.